Molecular cloning of a mouse epithelial protein‐tyrosine phosphatase with similarities to submembranous proteins

Publisher Website
Google Scholar
Abstract
Protein‐tyrosine phosphatases (PTPases) form an important class of cell regulatory proteins. We have isolated overlapping cDNA clones that together comprise an 8 kb transcript encoding a novel murine PTPase which is expressed in various organs. Sequence analysis revealed an open reading frame of 2,460 amino acid residues. The predicted protein, PTP‐BL, is a large non‐transmembrane PTPase that exhibits 80% homology with PTP‐BAS, a recently described human PTPase. PTP‐BL shares some intriguing sequence homologies with submembranous proteins. It contains a band 4.1‐like motif also present in the tumor suppressors neurofibromatosis 2 and expanded, five 80 amino acid repeats also present in the disc‐large tumor suppressor, and a single catalytic phosphatase domain. No obvious homologies to other proteins were found for the N‐terminal region of the protein other than human PTP‐BAS. RNA in situ hybridization experiments show that the PTP‐BL gene is expressed in epithelial cells, predominantly in kidney, lung, and skin. These data suggest a cell cortical localization for PTP‐BL in epithelial cells and a possible role in the morphology and motility of epithelial tissues.