Biology Department, Room: 141, Middle East Technical University, Ankara 06531, Turkey
The maturation of miRNA gene involves sequential process.
The miRNA genes are first transcribed in nucleus as long primary transcripts called pri-miRNA. The primary transcript for MIRN21 is found to be 3433-nt long.
For localization of the pri-MIRN21 transcript, total, nuclear and cytoplasmic RNA fractions from HeLa cells were oligo-dT primed and reverse transcribed into cDNA. pri-MIRN21 transcript was found mainly in the nucleus as well as modest levels in the cytoplasm.
Sequence: NCBI cDNA clone: BC053563.
The primary transcripts of microRNAs are processed by enzymatic microprocessor Drosha (RNase III enzyme) and DGCR8 (dsRNA binding protein) from their 3 and 5 cleavage sites into an intermediate stem-loop precursor or pre-miRNA in the nucleus.
The precursor of MIRN21 is 72 bases long (pre-MIRN21), forms a secondary structure, and contains the mature miRNA sequence, stem and terminal loop structures with 2-nt 3overhang (Figure 1; B). The precursor is then transferred from nucleus to cytoplasm by the enzyme Exportin 5. In cytoplasm, a second RNase III enzyme, Dicer, removes terminal loop generating about 20-bp RNA duplex.
Length: 72 bases
Sequence: UGUCGGGUAGCUUAUCAGACUGAUGUUGACUGUUGAAUCUCAUGGCAACACCAGUCGAUGGGCUGUCUGACA (Figure 1; B).
The mature miRNA forms one strand of the RNA duplex. One strand is degraded and other is incorporated in to a protein complex, RNA induced silencing complex (RISC), targeting a partially complementary target mRNA.
MIRN21 is 22 nucleotides long.
Sequence: UAGCUUAUCAGACUGAUGUUGA .
Sadan Duygu Selcuklu ; Mustafa Cengiz Yakicier ; Ayse Elif Erson
MIR21 (microRNA 21)
Atlas Genet Cytogenet Oncol Haematol. 2007-03-01
Online version: http://atlasgeneticsoncology.org/gene/44019/mir21-(microrna-21)