Tyrosine unphosphorylated platelet SHP-1 is a substrate for calpain. Biochem Biophys Res Commun 1998 Nov 09;252(1):51-5
Date
11/14/1998Pubmed ID
9813145DOI
10.1006/bbrc.1998.9593Scopus ID
2-s2.0-0032501155 (requires institutional sign-in at Scopus site) 23 CitationsAbstract
The platelet phosphotyrosine phosphatase (PTP) SHP-1 is tyrosine phosphorylated during thrombin-induced activation. Stimulation of platelets by the ionophore A23187 in the presence of CaCl2 induced a calpain dependent cleavage of SHP-1. SHP-1 proteolysis was undetectable during thrombin-induced stimulation. When SHP-1 was tyrosine phosphorylated by thrombin, further addition of A23187 failed to induce its cleavage. In the presence of tyrphostin to inhibit thrombin-induced SHP-1 tyrosine phosphorylation, SHP-1 was cleaved. Thus, only the tyrosine unphosphorylated form of SHP-1 was a substrate for calpain. A23187 induced the disappearance of all platelet phosphotyrosine proteins and a two-fold increase in PTP activity, both inhibited by pervanadate, a PTP inhibitor, but unaffected by calpeptin, a calpain inhibitor. The data show that SHP-1 is either tyrosine phosphorylated or cleaved by calpain, and suggest that SHP-1 cleavage does not contribute to A23187-induced PTP activity.
Author List
Falet H, Pain S, Rendu FAuthor
Herve Falet PhD Associate Professor in the Cell Biology, Neurobiology and Anatomy department at Medical College of WisconsinMESH terms used to index this publication - Major topics in bold
Blood PlateletsCalcimycin
Calcium Chloride
Calpain
Enzyme Activation
Humans
Intracellular Signaling Peptides and Proteins
Platelet Activation
Protein Tyrosine Phosphatase, Non-Receptor Type 11
Protein Tyrosine Phosphatase, Non-Receptor Type 6
Protein Tyrosine Phosphatases
SH2 Domain-Containing Protein Tyrosine Phosphatases
Substrate Specificity
Thrombin
Tyrosine
Vanadates
src Homology Domains