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Dephosphorylation of tyrosine phosphorylated synthetic peptides by rat liver phosphotyrosine protein phosphatase isoenzymes
Author(s) -
Stefani Massimo,
Caselli Anna,
Bucciantini Monica,
Pazzagli Luigia,
Dolfi Fabrizio,
Camici Guido,
Manao Giampaolo,
Ramponi Giampietro
Publication year - 1993
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(93)81776-v
Subject(s) - biochemistry , protein tyrosine phosphatase , dephosphorylation , peptide sequence , phosphorylation , peptide , tyrosine , microbiology and biotechnology , phosphatase , gene isoform , biology , receptor , chemistry , gene
Five phosphotyrosine‐containing peptides have been synthesized by FMOC solid‐phase peptide synthesis. These peptides correspond to the 411–419 sequence of the Xenopus src oncogene, to the 1191–1220 sequence of the human EGF receptor precursor, to the 1146–1158 sequence of the human insulin receptor, to the 856–865 sequence of the human, β‐PDGF receptor, and to the 5–16 sequence of the erythrocyte human band 3. The peptides were used as substrates for activity assay of two isoforms (AcP1 and AcP2) of a low molecular weight cytosolic PTPase. The assay, performed in microtiter E1A plates using Malachite green to determine the released phosphate, was rapid, reproducible, and sensitive. Both PTPase isoforms were able to hydrolyse all synthesized peptides, though with different affinity and rate. The main kinetic parameters were compared and discussed with respect to the role of the two enzymes in the cell.