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Assay of phosphotyrosyl protein phosphatase using synthetic peptide 1142–1153 of the insulin receptor
Author(s) -
King Martin J.,
Sale Graham J.
Publication year - 1988
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(88)80187-x
Subject(s) - phosphatase , dephosphorylation , protein tyrosine phosphatase , biochemistry , insulin receptor , phosphorylation , chemistry , peptide , insulin receptor substrate , receptor , insulin , biology , insulin resistance , endocrinology
Synthetic peptide 1142–1153 of the insulin receptor was phosphorylated on tyrosine by the insulin receptor and found to be a potent substrate for dephosphorylation by rat liver particulate and soluble phosphotyrosyl protein phosphatases. Apparent K m values were5 μM. V m values (nmol phosphate removed/min per mg protein) were 0.62 (particulate) and 0.2 (soluble). This corresponds to 80% of total activity being membrane‐associated, indicating that membrane‐bound phosphatases are important receptor phosphatases. The phosphatase activities were distinct from acid and alkaline phosphatase. In conclusion peptide 1142–1153 provides a useful tool for the further study and characterization of phosphotyrosyl protein phosphatases.