NGEP, a gene encoding a membrane protein detected only in prostate cancer and normal prostate.

We identified a gene (NGEP) that is expressed only in prostate cancer and normal prostate. The two NGEP transcripts are 0.9 kb and 3.5 kb in size and are generated by a differential splicing event. The short variant (NGEP-S) is derived from four exons and encodes a 20-kDa intracellular protein. The long form (NGEP-L) is derived from 18 exons and encodes a 95-kDa protein that is predicted to contain seven-membrane-spanning regions. In situ hybridization shows that NGEP mRNA is localized in epithelial cells of normal prostate and prostate cancers. Immunocytochemical analysis of cells transfected with NGEP cDNAs containing a Myc epitope tag at the carboxyl terminus shows that the protein encoded by the short transcript is localized in the cytoplasm, whereas the protein encoded by the long transcript is present on the plasma membrane. Because of its selective expression in prostate cancer and its presence on the cell surface, NGEP-L is a promising target for the antibody-based therapies of prostate cancer.