CHARACTERIZATION OF A PROTEIN-TYROSINE-PHOSPHATASE (RIP) EXPRESSED ATA VERY EARLY-STAGE OF DIFFERENTIATION IN BOTH MOUSE ERYTHROLEUKEMIA AND EMBRYONAL CARCINOMA-CELLS

From our previous studies, several protein tyrosine phosphatases (PTPa se) are implicated in the early events leading to in vitro differentia tion of both mouse erythroleukemia (MEL) and embryonal carcinoma (F9) cells. Among the PTPases, recent experiments suggest that a new PTPase (RIP) plays a critical role in differentiation processes, particularl y at their early stages. We isolated cDNA clones for RTP from a RNA pr eparation isolated from differentiating MEL cells, and determined the total 7932 bp base sequence for RIP cDNA. The cDNA codes for a putativ e 269.8 kDa (2450 amino acids) protein with a PTPase catalytic domain. We have demonstrated that the transcripts exist in multiple forms, an d among mouse tissues they were found predominantly in kidney and, to a lesser extent, in lung, heart, brain and testis. The RIP gene was ma pped between D5Mit90 and D5Mit25 on mouse chromosome 5.