CHARACTERIZATION OF RAT RECEPTOR-LIKE PROTEIN-TYROSINE-PHOSPHATASE-GAMMA ISOFORMS

We identified four isoforms of receptor-like protein tyrosine phosphat ase gamma (RPTP gamma) from rat brain by cDNA cloning. We designated t hese molecules RPTP gamma-A, -B, -C, and S. RPTP gamma-A was the longe st form and had the same structure as human and mouse RPTP gamma, RPTP gamma-B lacked the intracellular juxtamembrane 29 amino acids of RPTP gamma-A. RPTP gamma-C had a single phosphatase domain. RPTP gamma-S i s an extracellular variant of RPTP gamma. mRNAs of the four isoforms w ere expressed in the brain, kidney, lung, and heart, Transfection of R PTP gamma-A and -S expression plasmids into COS7 cells resulted in the expression of membrane bound 190-kDa proteins and secreted 120-kDa pr oteins, respectively, These molecules were similar to PTP zeta/RPTP be ta with regard not only to structure but also to the presence of both secretory and transmembrane forms. However, RPTP gamma isoforms were n ot expressed as proteoglycans. (C) 1997 Academic Press