KINETIC COMPARISON OF THE CATALYTIC DOMAINS OF SHP-1 AND SHP-2

Citation
Tq. Niu et al., KINETIC COMPARISON OF THE CATALYTIC DOMAINS OF SHP-1 AND SHP-2, Journal of cellular biochemistry, 72(1), 1999, pp. 145-150
Citations number
27
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Biology,"Cell Biology
ISSN journal
0730-2312
Volume
72
Issue
1
Year of publication
1999
Pages
145 - 150
Database
ISI
SICI code
0730-2312(1999)72:1<145:KCOTCD>2.0.ZU;2-#
Abstract
The phosphatase activity of SH2-containing protein tyrosine phosphatas e (SHP) is inhibited by its SH2 domains and C-terminal tail. In order to determine the inhibitory effects of the SH2 domains and C-terminal tail, we have expressed and purified the catalytic domains of SHP-1 an d SHP-2, and the SH2 domain truncated SH P-l and SHP-2. We have then m easured their kinetic parameters using p-nitrophenyl phosphate (p-NPP) and phosphotyrosine (pY) as substrates under the same experimental co nditions. The results indicate that the pH-dependent profiles of SHP-1 and SHP-2 are mainly determined by their catalytic domains. Both enzy mes have maximum activity at pH 5.0. In addition, the phosphatase acti vity of different forms of SHP-1 and SHP-2 decreases as the salt conce ntration increases. Without SH2 domains, both SHP-1 and SHP-2 are no l onger inhibited by their C-terminal tails. However, the C-terminal tai l of SHP-1 can further prevent the salt inhibition of the phosphatase activity. Under the same experimental conditions, the catalytic domain of SHP-1 is two times more active than the catalytic domain of SHP-2. ). Cell. Biochem. 72:145-150, 1999. (C) 1999 Wiley-Liss, Inc.