Isolation and partial characterization of distinct species of phosphotyrosyl protein phosphatases from rat spleen.

Three phopshotyrosine protein phosphatases (PTP-I PTP-II and PTP-III) inhibited by Zn2+ and active on the phosphotyrosyl residues included into the acidic co-polymer poly (Glu, Tyr) 4:1 previously phosphorylated by a spleen tyrosyl kinase have been resolved and partially purified from rat spleen cytosol by DEAE cellulose chromatography followed by phosphocellulose chromatography and/or Ultrogel AcA 44 gel filtration. PTP-I (Mr 65,000 by gel filtration) was purified about 1000 folds. It is stimulated by EDTA and unaffected by either vanadate (50 μM) or molybdate (up to 25 μM). PTP-II (Mr 30,000) and PTP-III (Mr 50,000) are insensitive to EDTA and inhibited by molybdate. In addition PTP-III is also inhibited by vanadate. © 1985.