Multiple promoter and splicing mRNA variants of the epididymis-specific gene EP2.

The EP2 gene codes for a family of androgen-dependent, epididymis-specific secretory proteins. Using probes derived from human HE2 cDNA, a chimpanzee epididymal cDNA library was screened. Five variants of chimpanzee EP2 cDNA were identified. Variant 1 (EP2A) is the chimpanzee ortholog of HE2. Variant 2 (EP2B) has an alternative 5' end. Variant 3 (EP2C) has an alternative 3' end. Two additional variants were identified by reverse transcriptase-polymerase chain reaction analysis. Variant 4 (EP2D) and variant 5 (EP2E) appear to lack an exon, resulting in a shift in the open reading frame. Presumably, the 5 variants originate from the same gene and result from alternative promoters and alternative splicing. Each of the putative proteins encoded by these variant messages has a leader sequence characteristic for a secretory protein. After removal of the leader sequence, each of these proteins is predicted to consist of 1 or 2 out of 4 possible peptide modules. Two of these modules have no recognizable homology to known proteins. The other 2 modules have a distribution of cysteine residues characteristic for beta-defensins, a family of proteins with antimicrobial activity.