The PERP gene is of 19019 bases and localized on the minus strand. PERP encompasses three exons (NCBI, 2014).

4319 bp long mRNA; 582 bp long open reading frame (NM_022121.4).

No reported pseudogenes.

PERP encodes a 193 amino acid long tetraspan membrane protein (Attardi et al., 2000). Perp has a molecular mass of 21 kDa with an isoelectric point of 6.68 (Franke et al., 2013).

PERP is expressed in the tongue mucosa, cornea, heart, lung (Chen et al., 2011) simple, columnar, complex, transitional and stratified epithelia of human, bovine, porcine and murine (Franke et al., 2013) and teeth (Jheon et al., 2011; Neupane et al., 2014). PERP is also expressed in the primary choroidal melanoma (Paraoan et al., 2006) and in cell lines derived from breast, prostate, colon, cervix and pancreas tumors (Hildebrandt et al., 2001).

Perp exhibits a punctuated pattern of localization at the plasma membrane and interdesmosomal regions (Franke et al., 2013) and colocalizes with desmosomal components (Attardi et al., 2000; Davies et al., 2009; Singaravelu et al., 2009). Perp is also suggested to localize at the perinuclear region and endoplasmic reticulum/golgi apparatus in primary uveal melanoma (UM) cells (Davies et al., 2009).

PERP is a transcriptional target of p53 and p63 transcription factors acting alone or in concert to homeodynamically modulate cellular responses. The expression of PERP appears to be independent of p53 in embryogenesis but is dependent upon p63. The interaction of p53 or p63 with several response elements of varying affinities on the PERP locus is responsible for the PERP expression. The regulation of PERP transcription by p63 in epithelial-specific manner during embryogenesis is critical for the stratified epithelial development through functions of Perp at desmosomes (Attardi et al., 2000; Ihrie et al., 2005). The absence of Perp as studied in a PERP knockout mouse model is manifested as defects in the assembly and maintenance of desmosomes (Ihrie et al., 2005). Perp is also shown to participate in skin and notochord development of zebrafish (Nowak et al., 2005). The mediation of PERP expression by p53 results in apoptosis independent of cell cycle arrest. The expression of PERP is shown to increase during apoptosis, but not upon induced G1 arrest in mouse embryonic fibroblasts (Attardi et al., 2000). Induction of PERP expression induces apoptosis through the activation of caspase-8 in primary UM cell lines (Davies et al., 2009). Similarly, the overexpression of PERP at the outer medullary proximal tubular cells of ischemic kidneys in response to hypoxia appears to augment apoptosis by inducing mitochondrial permeability and cytochrome c release as well as by activating apoptosis-inducing factor (AIF) and caspase 9 proteins (Singaravelu et al., 2009).
These findings collectively indicate that Perp is an important mediator of stratified epithelial development, cell adhesion and apoptosis through desmosomal activities.

Perp shares amino acid sequence similarities with peripheral myelin protein 22/growth arrest specific 3 (PMP-22/gas3) tetraspan membrane protein family, which is associated with growth regulation (Attardi et al., 2000).