title: A phosphotyrosyl-protein phosphatase activity associated with acid phosphatase from human prostate gland.
abstract: Using [32P]P-Tyr-IgG and [32P]P-Tyr-casein phosphorylated by pp60v-src as substrates, studies on the phosphotyrosyl-protein phosphatase activity in human prostate gland indicate that it is associated with prostatic acid phosphatase. Evidence to support this conclusion include the following: (a) these two enzymatic activities co-purify to apparent homogeneity; (b) they co-migrated on polyacrylamide gel electrophoresis, ion-exchange and gel filtration chromatographies; (c) the exhibit identical thermostability; and (d) the phosphotyrosyl-protein phosphatase activity is sensitive to inhibition by p-nitrophenyl phosphate and by several classical inhibitors of prostatic acid phosphatase including L(+)-tartrate, molybdate, vanadate and NaF. The purified enzyme exhibits high specificity towards phosphotyrosyl-proteins with little activity towards several phosphoseryl-proteins and phosphothreonyl-proteins examined. The present findings indicate that prostatic acid phosphatase may function in vivo as a phosphotyrosyl-protein phosphatase.
mesh_terms: D000135:Acid Phosphatase / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D008297:Male; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors / Q000302:isolation & purification / Q000378:metabolism*; D011467:Prostate / Q000201:enzymology*; D013379:Substrate Specificity
chemical_list: D010749:Phosphoprotein Phosphatases; D000135:Acid Phosphatase