Proteolipid Protein 2, Colonic Epithelium Enriched (PLP2)

PLP2 encodes an integral membrane protein that localizes to the endoplasmic reticulum in colonic epithelial cells. The encoded protein can multimerize and may function as an ion channel. A polymorphism in the promoter of this gene may be linked to an increased risk of X-linked mental retardation. A pseudogene of this gene is found on chromosome 5. Oliva et al. (1993) cloned a cDNA encoding the A4 differentiation-dependent protein from a human colon cell line. Fisher et al. (1997) identified the promoter and complete coding sequence of the A4 gene, which is organized into 5 exons spanning approximately 3.5 kb of DNA. The product of this gene is an integral membrane protein, containing 4 putative transmembrane domains that may play a role in cell differentiation in the intestinal epithelium.