SRC KINASE ASSOCIATES WITH A MEMBER OF A DISTINCT SUBFAMILY OF PROTEIN-TYROSINE PHOSPHATASES CONTAINING AN EZRIN-LIKE DOMAIN

A 6.2-kb full-length clone encoding a distinct protein-tyrosine phosph atase (PTP; EC 3.1.3.48), PTPD1, was isolated from a human skeletal mu scle cDNA library. The cDNA encodes a protein of 1174 amino acids with N-terminal sequence homology to the ezrin-band 4.1-merlin-radixin pro tein family, which also includes the two PTPs H1 and MEG1. The PTP dom ain is positioned in the extreme C-terminal part of PTPD1, and there i s an intervening sequence of about 580 residues without any apparent h omology to known proteins separating the ezrin like and the PTP domain s. Thus, PTPD1 and the closely related, partially characterized, PTPD2 belong to the same family as PTPH1 and PTPMEG1, but because of distin ct features constitute a different PTP subfamily. Northern blot analys es indicate that PTPD1 and PTPD2 are expressed in a variety of tissues . In transient coexpression experiments PTPD1 was found to be efficien tly phosphorylated by and associated with the src kinase pp60(src).