CD81 (Cluster of Differentiation 81)

2019-09-01   Sylwia Hasterok , Barnabas Nyesiga , Anette Gjörloff-Wingren 

Identity

HGNC
LOCATION
11p15.5
IMAGE
Atlas Image
LEGEND
Figure 1. Mapping of CD81 gene on chromosome 11p15.5 (from Ensembl CD81 gene). Source: Ensembl data base (https://www.ensembl.org/Homo_sapiens/Location/View?db=core;g=ENSG00000110651;r=11:2376177-2397419
LOCUSID
ALIAS
CVID6,S5.7,TAPA1,TSPAN28

Abstract

Cluster of differentiation (CD81) is a type of protein, which is encoded by CD81 gene. Beside that CD81 is also known under other names such as Target of the Antiproliferative Antibody 1 (TAPA-1) and Tetraspanin-28 (TSPAN28). Location of CD81 is known to be on chromosome 11 (11p15.5), where it contains 15-20 bases in length. It is expressed mostly in cells of testis, ovary, endometrium, placenta, bone marrow, smooth muscles and others. The main function of the CD81 protein is to mediate signal transduction events, which are important for cells development, activation, growth and motility. The CD81 gene is also known as a candidate for many malignancies because of its location. The characteristic feature of CD81 is that it is highly hydrophobic and contains a short N- and C-terminal cytoplasmic domains together with cytoplasmic cysteines, potential sites of palmitoylation as well as four transmembrane domains where they together hold the protein in a cell membrane. There are two CD81 isoforms, isoform 1 and isoform 2. Isoforms of CD81 are usually found in a tumor-suppressor region where they have a great impact on tumor development. There has always been a high interest in research on CD81 function in viral disease development. In fact, it is known that CD81 contributes in the development of diseases such as hepatitis C, malaria and various types of cancer. Since the complete effect of CD81 is unknown, further research and scientific methodology could potentially discover all possible functions and mechanisms regulated by the CD81 protein in human body.

DNA/RNA

Note

The highest level of CD81 gene expression is in endometrium (RPKM 241.8), fat (RPKM 237.1), lung (RPKM 191.2) and 24 other tissues in the human body. Proteins encoded by the CD81 gene are important for transduction of signals, cell development, growth and motility (RefSeq NCBI et al., 2019).
Atlas Image
Figure 2. Homo sapiens CD81 molecule RefSeqGene (LRG_142) on chromosome 11. (RefSeq NCBI et al., 2019).

Description

Cluster of Differentiation 81 (CD81) is a type of protein, which belongs to tetraspanin family of proteins (Thomas and Mohler, 2011). According to the study, it is an important molecule for the biological system of living organisms that regulates several types of mechanisms in the body (Thomas and Mohler, 2011). The molecule was previously known as TAPA-1 but changed its name to CD81, after the Fifth International Workshop on Human Leukocyte Differentiation Antigens (IUIS/WHO Subcommittee on CD Nomenclature, 1994).
CD81 gene constitutes a protein coding gene which is located in the chromosomal region 11p15.5 of human genome. Using 5A6 (immunoglobulin- γ1), a monoclonal antiproliferative antibody, Oren et al. (1990) performed the first isolation of cDNAs encoding CD81. The chromosomal localization of CD81 gene in the short arm of chromosome 11 was determined by Andria et al. (1991) in Southern blot experiments in which DNA isolated from somatic cell hybrids was used. In order to assign CD81 gene to a specific region on the chromosome 11, Virtaneva et al. (1994) performed experiments by hybridizing CD81 gene to derivative somatic cell hybrid DNAs of human chromosome 11. The exact location of CD81 gene is shown in the figure 1. To date, 17 transcript variants have been found for this gene.
As indicated by Andria et al. (1991), the 5 untranslated region of the CD81 gene is abundant in CpG islands, which is a common feature observed in many housekeeping genes (Andria et al.,1991; Levy et al., 1998). High content of G + C nucleotides in this region correlates with a high susceptibility to methylation events, which can affect the expression of the receptor (Houldsworth et al., 2013). It also contains a TATA box at -25 position and presumably, binding sites for SP1 transcription factor (Maecker et al., 1997). Additionally, it has been reported that the region in which CD81 gene is located constitutes a tumor-suppressor region, which makes a CD81 gene an important candidate for various malignancies.

Transcription

There are several ongoing studies regarding the CD81 gene due to its transcriptional activity (Hong et al., 2014; Tardif et al., 2005). In an experiment in which promoter analysis was performed, it has been shown that there is an essential role of the SP1 transcription factor in CD81-induced MT1-MMP transcription (Hong et al., 2014). Having CD81 with high MT1-MMP expression levels is of a great importance since it is associated with malignant melanoma development (Hong et al., 2014). The antigen itself is very much vital for the malignancies, primarily due to the location of the CD81 gene in a tumour-suppressor region (Levy et al., 2014). Mature transcript of CD81 is made of eight exons, all of which code information for protein synthesis. The transcript itself is 1,714 bp long.

Proteins

Atlas Image
Figure 3. CD81 structure (Levy, 2014).

Description

CD81 antigen, previously known as TAPA1, constitues a membrane protein of 26-kDa molecular weight, which is expressed in many cell types, including hemopoietic, endothelial as well as epithelial cells. It is a founding member of a highly conserved tetraspan family of transmembrane 4 superfamily, also known as tetraspanin family. Members of this family are expressed not only in mammals, but also in all other multicellular organisms, including insects such as Drosophila, plants as well as fungi.
FFIL CD81 is a highly hydrophobic protein which contains a short N- and C-terminal cytoplasmic domains with cytoplasmic cysteins, potential sites of palmitoylation as well as four transmembrane domains (TM 1-4) that hold the protein in a cell membrane. The protein folds itself creating a large extracellular loop (LEL) with CCG motif and two disulfide bridges, small extracellular loop (SEL) and even a smaller loop of intracellular location (Levy, 2014). Unlike many other members of the family, CD81 does not undergo glycosylation. The protein exibits a strong homology with two antigens - CD37 (65% identical) as well as ME491 melanoma-associated antigen (98% identical) also known as CD63 molecule. Originally, CD81 protein was characterized as a target of an antiproliferative antibody that leads to the inhibition of B cell proliferation (Levy, 2014).
C According to the Zimmerman et al. (2016), transmembrane parts of CD81 contain two largely disconnected couples of spirals, covered with a bulky extracellular loop at the exterior membrane leaflet. These two sets of coils converge at the position of internal leaflet to generate an intramembrane abridged with supplementary electron concentration corresponding to a cholesterol molecule in a cavity. Molecular subtleties simulation recognizes a supplementary conformation in which extracellular loop splits considerably from the transmembrane domain. Cholesterol binding appears to modulate CD81 activity in cells, signifying a probable mechanism for regulation of tetraspanin occupation.
Atlas Image
Figure 4. Model of CD81 protein (Source: SWISS-MODEL https://swissmodel.expasy.org/interactive)

Expression

On a protein level the expression of CD81 occurs on B-cells, hepatocytes, monocytes/macrophages and on both naive and memory CD4-positive T cells (Takeda et al., 2003; Silvie et al., 2003; van Zelm et al., 2010; Sagi et al., 2012)
Atlas Image
Figure 5. Structure of CD81 protein (Source: UNIPORT https://www.uniprot.org/uniprot/P60033)

Localisation

CD81 gene can be localised in the tumor-suppressor region where two different isoforms can be found.
Atlas Image
Figure 6. CD81 isoform 1. Location 10-228 (RefSeq NCBI et al., 2019)
Atlas Image
Figure 7. CD81 isoform 2. Location 42-131 (RefSeq NCBI et al., 2019).
Atlas Image
Figure 8. CD81-cholesterol interactions (Zimmerman et al., 2016).

Function

CD 81 plays a significant role in several physiological functions such as regulation of cell activation, development, motility and growth (Fagerberg et al., 2014). It is also involved in signal transduction. CD81 encoded glycoprotein associated with the cell surface is known to create a complex with integrins, which helps to promote fusion of muscle cells as well as maintenance of myotubes.
According to Thomas and Mohler (2011), CD81 is expressed on the surface of oocytes and absence of this molecule is associated with a reduced fertility in the mice system due to egg-sperm fusion defects. On the other hand, Kaji et al. (2002) proved that CD81 and CD9 have corresponding utilities in the egg-sperm fusion. The activity of CD9 is reduced by the absence of the CD81 which was observed in the mice model system. There are several reports available in which it has been proven that CD81 actively prevents development of some viral diseases like hepatitis C virus (Nalesnik and Kanto, 2010). Geisert et al. (2002) showed that CD81 is involved in the development of the central nervous system. According to the experiment, in comparison to normal mice, CD81 mutation in the cells of central nervous system results in the development of 30% larger brains.
When CD81 is increased in the body, it may be promoting breast cancer. Scientific study designed by Zhang et al. (2018) on MDA-MB-435S and MDA-MB-231 human breast cancer cell lines showed that when CD81 expression increases as an effect it can promote breast cancer. Malaria parasite Plasmodium uses CD81 membrane protein to attack liver cells in a human body (Bruening et al., 2018). It is also known that CD81 has an ability to bind to cholesterol where the amount of cholesterol controls the expression of CD81 (van Zelm et al., 2010; Vences-Catalán et al., 2015).

Homology

Highest homology level of CD81 protein can be found between humans and mice (Boismenu et al., 1996). By analysing the homology between human and mouse variants, it has been shown that the transmembrane domain residues are mostly sequentially conserved. Beside that it has been also proven that extracellular domains significantly differ from each other as presented in a figure 9 (Frolikova et al., 2018). The protein exhibits a strong homology with two antigens - CD37 (65% identical) as well as ME491, melanoma-associated antigen (98% identical) also known as CD63 molecule (Levy et al., 2014).
Atlas Image
Figure 9. CD81 in human and mouse (Frolikova et al., 2018). Figure 9 presents the transmembrane domain residues and differences between extracellular domains. The whole protein consists of non-identical acids between human and mouse CD81 and CD9 projected onto the model of CD9/CD81 complex. The difference is the amount of amino acids where CD81 contains 17 different amino acids in the extracellular domain while CD9 differs in 25 amino acids on same location (Frolikova et al.,2018).

Mutations

Note

Mutations associated with CD81 are often caused by viral infections such as hepatitis C. According to the study where the hepatitis C virus envelope protein (E)2 interacts with cellular receptor CD81 it was possible to obtain the modulation of B and T cell function. Despite positive results, the importance of the mutation is unknown even though the mutation was caused by the modulation of these two proteins as well as the effect and the correlation between CD81 and binding regions of HCV Geno/subtypes (Kronenberger B et al., 2004).
Mutations associated with CD81 are often caused by viral infections such as hepatitis C. According to the study where the hepatitis C virus envelope protein (E)2 interacts with cellular receptor CD81 it was possible to obtain the modulation of B and T cell function. Despite positive It is known that CD19 and CD81 depend on each other regardless if the mutation occurs or not. Dependence was described on a group of patients with an increased susceptibility to infection, hypogammaglobulinemia, and normal numbers of mature B cells in blood, but all the patients had a mutation in CD19 in common (van Zelm et al., 2006). Usually, CD81 is expressed on blood cells such as blood lymphocytes, monocytes, basophilic granulocytes, and eosinophils. The absence of CD81 in membrane has never been found in humans before. However, a study performed on B cells from 611 neonatal cord blood samples showed that the absence can occur (Duijts et al., 2009).
Mutations associated with CD81 are often caused by viral infections such as hepatitis C. According to the study where the hepatitis C virus envelope protein (E)2 interacts with cellular receptor CD81 it was possible to obtain the modulation of B and T cell function. Despite positive In a study where a patient had severe nephropathy and profound hypogammaglobulinemia as well as immunodeficiency with decreased memory B cell numbers, with help of DNA sequencing of all 8 exons in which homozygous G>A substitution was found, splice sites were directly identified downstream of exon 6: c.561+1G>A. This kind of exons cause frameshift before the fourth transmembrane domain as well as premature stop (p. Glu188MetfsX13). Because of the mutation, the splice donor site was disrupted and sixth intron in cryptic splice site was used (van Zelm et al., 2010).
Atlas Image
Figure 10. Presentation of the CD81 gene with 8 exons. Patient who participated in the study was homozygous for a splice site mutation downstream of exon 6 (exon6+1 G>A). This is resulting in the usage of a cryptic splice site 13 nucleotides downstream of exon 6. Premature stop codon upstream of the fourth transmembrane domain of the CD81 protein, TM transmembrane domain; SEL, short extracellular loop; LEL, large extracellular loop as well as frameshift are caused by the insertion of the 13-nucleotide region (van Zelm et al., 2010).

Somatic

CD81 also has an ability to regulate CD19 in B-lymphocytes, which can trigger the progression of hepatitis C virus infection in human cells. Scientific research in which human cells underwent a procedure of immunohistological staining proved that normal hematopoietic tissue resulted in a strong staining for CD81 in a normal germinal centre B cell. Another analytical method called high-dimensional flow cytometry confirmed that among B and T cell subsets, germinal centre B cells had the highest level of CD81 expression (Luo et al., 2010). Moreover, scientific study performed on mice showed that there is a correlation between the amount of CD81 and CD9 presented in somatic cells with successful fertilisation of spices. It is proven that the lack of CD81 and CD9 leads to a lower chance of successful fertilisation. In somatic cells, CD81 and CD9 associate with each other together with other, non-tetraspanin molecules, creating proteolipid complexes. Artificial removal of CD81 gene in mice leads to 40% reduction of female fertility (Rubinstein et al., 2006).

Epigenetics

Cluster analysis have found 25 types of genes that were hypermethylated and hypomethylated, respectively, in 20% in all of the studies. One of the most frequently hypermethylated genes was CD81. CD81 has been found in larger amounts as target of polycomb repressive complex 2 in embryonic stem cells in a medical condition called Glioblastoma multiforme, a devastating brain tumor in adults. CD81 is a member of membranal-embedded tetraspanin superfamily and it is usually observed in multiple myelomas. Tetraspanin genes associated with signalling proteins modulate fundamental biological functions and can potentially be involved in CD81 gene as a metastasis suppressor (Martinez et al., 2009).

Implicated in

Top note
The CD81 protein is a highly involved in the development of several diseases including hepatitis C, malaria, several types of cancer, HIV, fungal diseases, parasites etc. The main mechanism involves CD81 acting as a signalling molecule with a pathogen attached to the extracellular loop of CD81. This means that it acts as a getaway for the infection. It has also been proven that CD81 is important for the immune system due to its close association with CD19 in B cells. Simultaneously, it plays an important role in T cells by acting as a costimulatory agent for CD3 (Vences-Catalán et al., 2015). Presumably, further research on CD81 may provide information on all other possible functions and mechanisms of action of this molecule (Monk and Partridge, 2012).
Entity name
Hepatitis C
Note
Research on hepatitis C virus and CD81 has always been of a high interest. CD81 is considered to be a central regulator involved in the HCV lifecycle. It has been proven that due to its location in the cell membrane of hepatocytes, CD81 interacts with HCV entry factors and by that it plays a key role in the initiation of infection. The HCV infection begins when viral particles bind to glycosaminoglycans (GAG) as well as Low Density Lipoproteins Receptors (LDL-R), which are non-specific factors located on the cell surface. This stage is then followed by a direct interaction of HCV with an entry factors which are cell specific. Among these factors, CD81 constitutes the most studied and the best characterized entry factor involved in the HCV infection (Pileri et al., 1998; Cormier et al., 2004; Fu00e9nu00e9ant et al., 2014). Pileri et al. (1998) demonstrated that the virus protein E2 binds large extracellular loop of CD81 protein and that the disruption of the E2-CD81 interaction, resluts in hindering of the HCV entry and infection.
Entity name
Malaria
Note
Malaria parasites such as Plasmodium yoelii and Plasmodium falciparum sporozoites are involved in the CD81 expression. In a study where correlation of CD81 and malaria infection has been analysed, direct link between CD81 and cholesterol during the infection of malaria parasites has been shown. Additionally, it has been proven that the loops of these tetraspanins contain a new type of microdomains that potentially could be used by pathogens for infection (Silvie et al., 2006).
Entity name
Breast cancer
Note
The role of CD81 protein in breast cancer is unknown (Zhang et al., 2018). According to the scientific study the expression of CD81 during breast cancer state is significantly increased compared to the normal breast tissue. The increase of CD81 is associated with lymph node metastasis. (Zhang et al., 2018). It has been concluded that CD81 may be used as a prognostic biomarker associated with poor patient prognosis in breast cancer (Zhang et al., 2018).
Entity name
Hepatocellular carcinoma
Note
CD81 is known to be a receptor for hepatitis C. This kind of characteristic is a major cause of hepatocellular carcinoma (Charrin et al., 2001).
Entity name
Acute myeloid leukaemia (AML)
Note
The medical condition AML is known to be heterogeneous disease and lately, novel prognostic factors have been of a great importance in order to propose appropriate therapy. CD81 does have negative impact on survival outcome in AML patients. It is known that CD81 could be used in therapeutic approaches in stating proper AML treatment. Further studies are needed in order to confirm prognostic impact of CD81 and AML (Boyer et al., 2016).
Entity name
HIV infection
Note
Some reports have indicated that CD81 is associated with CD4, which provides a costimulatory signal that increases HIV-1 gene expression (Gordón-Alonso et al., 2006) CD81 has the ability to deliver a co-signal for T cells. This action triggers cytokine production, which leads to the cellular proliferation. Signalling processes are initiated through the T-cell receptor (TCR)/CD3 complex where coactivator CD28 affects immunodeficiency virus type 1 (HIV-1) gene expression. According to Tardig et al. (2005) no study has investigated the putative costimulatory activity of CD81 on HIV-1 transcriptional activity.

Bibliography

Pubmed IDLast YearTitleAuthors
16503851991Genomic organization and chromosomal localization of the TAPA-1 gene.Andria ML et al
85396181996A role for CD81 in early T cell development.Boismenu R et al
275665552016Tetraspanin CD81 is an adverse prognostic marker in acute myeloid leukemia.Boyer T et al
300249682018Hepatitis C virus enters liver cells using the CD81 receptor complex proteins calpain-5 and CBLB.Bruening J et al
79550321994CD antigens 1993: an updated nomenclature for clusters of differentiation on human cells. IUIS/WHO Subcommittee on CD Nomenclature.
112788802001The major CD9 and CD81 molecular partner. Identification and characterization of the complexes.Charrin S et al
151238132004CD81 is an entry coreceptor for hepatitis C virus.Cormier EG et al
187767292009Fetal growth influences lymphocyte subset counts at birth: the Generation R Study.Duijts L et al
245098092014CD81 and hepatitis C virus (HCV) infection.Fénéant L et al
243098982014Analysis of the human tissue-specific expression by genome-wide integration of transcriptomics and antibody-based proteomics.Fagerberg L et al
296717632018CD9 and CD81 Interactions and Their Structural Modelling in Sperm Prior to Fertilization.Frolikova M et al
123574292002Increased brain size and glial cell number in CD81-null mice.Geisert EE Jr et al
170156972006Tetraspanins CD9 and CD81 modulate HIV-1-induced membrane fusion.Gordón-Alonso M et al
247333932014The tetraspanin CD81 protein increases melanoma cell motility by up-regulating metalloproteinase MT1-MMP expression through the pro-oncogenic Akt-dependent Sp1 activation signaling pathways.Hong IK et al
241227772014CD81 sequence and susceptibility to hepatitis C infection.Houldsworth A et al
120864702002Infertility of CD9-deficient mouse eggs is reversed by mouse CD9, human CD9, or mouse CD81; polyadenylated mRNA injection developed for molecular analysis of sperm-egg fusion.Kaji K et al
152308532004Mutations in the putative HCV-E2 CD81 binding regions and correlation with cell surface CD81 expression.Kronenberger B et al
245226982014Function of the tetraspanin molecule CD81 in B and T cells.Levy S et al
18608631991Structure and membrane topology of TAPA-1.Levy S et al
95971251998CD81 (TAPA-1): a molecule involved in signal transduction and cell adhesion in the immune system.Levy S et al
200040012010CD81 protein is expressed at high levels in normal germinal center B cells and in subtypes of human lymphomas.Luo RF et al
91945231997The tetraspanin superfamily: molecular facilitators.Maecker HT et al
195501452009A microarray-based DNA methylation study of glioblastoma multiforme.Martinez R et al
220349322012Tetraspanins: gateways for infection.Monk PN et al
16953201990TAPA-1, the target of an antiproliferative antibody, defines a new family of transmembrane proteins.Oren R et al
97947631998Binding of hepatitis C virus to CD81.Pileri P et al
163801092006Reduced fertility of female mice lacking CD81.Rubinstein E et al
223076192012Complementary costimulation of human T-cell subpopulations by cluster of differentiation 28 (CD28) and CD81.Sagi Y et al
217499012011New insights into the mechanisms and roles of cell-cell fusion.Shinn-Thomas JH et al
166877362006Cholesterol contributes to the organization of tetraspanin-enriched microdomains and to CD81-dependent infection by malaria sporozoites.Silvie O et al
124832052003Hepatocyte CD81 is required for Plasmodium falciparum and Plasmodium yoelii sporozoite infectivity.Silvie O et al
127964802003Tetraspanins CD9 and CD81 function to prevent the fusion of mononuclear phagocytes.Takeda Y et al
157674322005Tetraspanin CD81 provides a costimulatory signal resulting in increased human immunodeficiency virus type 1 gene expression in primary CD4+ T lymphocytes through NF-kappaB, NFAT, and AP-1 transduction pathways.Tardif MR et al
299463182018Immune Targeting of Tetraspanins Involved in Cell Invasion and Metastasis.Vences-Catalán F et al
81688501994Chromosomal localization of three human genes coding for A15, L6, and S5.7 (TAPA1): all members of the transmembrane 4 superfamily of proteins.Virtaneva KI et al
301174942018Increased Expression of CD81 in Breast Cancer Tissue is Associated with Reduced Patient Prognosis and Increased Cell Migration and Proliferation in MDA-MB-231 and MDA-MB-435S Human Breast Cancer Cell Lines In Vitro.Zhang N et al
278813022016Crystal Structure of a Full-Length Human Tetraspanin Reveals a Cholesterol-Binding Pocket.Zimmerman B et al
202374082010CD81 gene defect in humans disrupts CD19 complex formation and leads to antibody deficiency.van Zelm MC et al

Other Information

Locus ID:

NCBI: 975
MIM: 186845
HGNC: 1701
Ensembl: ENSG00000110651

Variants:

dbSNP: 975
ClinVar: 975
TCGA: ENSG00000110651
COSMIC: CD81

RNA/Proteins

Gene IDTranscript IDUniprot
ENSG00000110651ENST00000263645P60033
ENSG00000110651ENST00000263645A0A024RCB7
ENSG00000110651ENST00000381036A6NMH8
ENSG00000110651ENST00000464784H0YDL9
ENSG00000110651ENST00000475945E9PM31
ENSG00000110651ENST00000481687E9PIF1
ENSG00000110651ENST00000492252E9PRJ8
ENSG00000110651ENST00000492627E9PJK1
ENSG00000110651ENST00000493525E9PQV4
ENSG00000110651ENST00000526072E9PJK1
ENSG00000110651ENST00000527343H0YDJ9
ENSG00000110651ENST00000530648E9PPF5
ENSG00000110651ENST00000533417H0YEE2

Expression (GTEx)

0
500
1000
1500

Pathways

PathwaySourceExternal ID
B cell receptor signaling pathwayKEGGko04662
B cell receptor signaling pathwayKEGGhsa04662
MalariaKEGGko05144
MalariaKEGGhsa05144
Hepatitis CKEGGko05160
Hepatitis CKEGGhsa05160
Immune SystemREACTOMER-HSA-168256
Adaptive Immune SystemREACTOMER-HSA-1280218
Immunoregulatory interactions between a Lymphoid and a non-Lymphoid cellREACTOMER-HSA-198933

Protein levels (Protein atlas)

Not detected
Low
Medium
High

References

Pubmed IDYearTitleCitations
129130012003Cell entry of hepatitis C virus requires a set of co-receptors that include the CD81 tetraspanin and the SR-B1 scavenger receptor.221
191489422009Development and characterization of hepatitis C virus genotype 1-7 cell culture systems: role of CD81 and scavenger receptor class B type I and effect of antiviral drugs.170
179410582008Hepatitis C virus cell-cell transmission in hepatoma cells in the presence of neutralizing antibodies.151
147223002004CD81 is required for hepatitis C virus glycoprotein-mediated viral infection.150
169123172006Identification of conserved residues in the E2 envelope glycoprotein of the hepatitis C virus that are critical for CD81 binding.127
124832052003Hepatocyte CD81 is required for Plasmodium falciparum and Plasmodium yoelii sporozoite infectivity.114
151238132004CD81 is an entry coreceptor for hepatitis C virus.109
202374082010CD81 gene defect in humans disrupts CD19 complex formation and leads to antibody deficiency.102
170792812007The level of CD81 cell surface expression is a key determinant for productive entry of hepatitis C virus into host cells.101
175222072007Human immunodeficiency virus type 1 assembly, budding, and cell-cell spread in T cells take place in tetraspanin-enriched plasma membrane domains.101

Citation

Sylwia Hasterok ; Barnabas Nyesiga ; Anette Gjörloff-Wingren

CD81 (Cluster of Differentiation 81)

Atlas Genet Cytogenet Oncol Haematol. 2019-09-01

Online version: http://atlasgeneticsoncology.org/gene/991/cd81-(cluster-of-differentiation-81)