Enzyme kinetic characterization of protein tyrosine phosphatases.
Protein tyrosine phosphatases (PTPs) play a central role in cellular signaling processes, resulting in an increased interest in modulating the activities of PTPs. We therefore decided to undertake a detailed enzyme kinetic evaluation of various transmembrane and cytosolic PTPs (PTPalpha, PTPbeta, PTPepsilon, CD45, LAR, PTP1B and SHP-1), using pNPP as substrate. Most noticeable is the increase in the turnover number for PTPbeta with increasing pH and the weak pH-dependence of the turnover number of CD45. The kinetic data for PTPalpha-D1 and PTPalpha-D1D2 suggest that D2 affects the catalysis of pNPP. PTPepsilon and the closely homologous PTPalpha behave differently. The K(m) data were lower for PTPepsilon than those for PTPalpha, while the inverse was observed for the catalytic efficiencies.
Peters
Günther H
GH
Department of Chemistry, Center for Biomembrane Physics (MEMPHYS), Technical University of Denmark, Building 206, DK-2800 Lyngby, Denmark. ghp@kemi.dtu.dk
Branner
Sven
S
Møller
Karin B
KB
Andersen
Jannik N
JN
Møller
Niels Peter H
NP
D000818:Animals; D015153:Blotting, Western; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry; D009596:Nitrophenols / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry; D017027:Protein Tyrosine Phosphatases / Q000737:chemistry*; D011993:Recombinant Fusion Proteins / Q000737:chemistry
D008565:Membrane Proteins; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D011993:Recombinant Fusion Proteins; C008644:nitrophenylphosphate; D017027:Protein Tyrosine Phosphatases