Biochemical characterization of a human band 4.1-related protein-tyrosine phosphatase, PTPH1

Zhang, S. H., Eckberg, W. R., Yang, Q., Samatar, A. A., Tonks, N. K. (August 1995) Biochemical characterization of a human band 4.1-related protein-tyrosine phosphatase, PTPH1. Journal of Biological Chemistry, 270 (34). pp. 20067-20072. ISSN 0021-9258

URL: http://www.ncbi.nlm.nih.gov/pubmed/7544351

Abstract

PTPH1 is a human protein-tyrosine phosphatase with homology to the band 4.1 superfamily of cytoskeleton-associated proteins, Here, we report the purification and biochemical characterization of this enzyme from baculovirus-infected insect cells. The purified protein exhibited an apparent M(r) of 120,000 on SDS gels. The native enzyme dephosphorylated both myelin basic protein (MBP) and reduced, carboxamidomethylated, and maleylated lysozyme (RCML) but was over 5-fold more active on MBP. The K-m values for the two substrates were similar (1.45 mu M for MBP and 1.6 mu M for RCML). Phosphorylation of PTPH1 by protein kinase C in vitro resulted in a decrease in K-m but had no effect on V-max. Removal of the NH2-terminal band 4.1 homology domain of PTPH1 by limited trypsin cleavage stimulated dephosphorylation of RCML but inhibited its activity toward MBP, The dephosphorylation of RCML by full-length PTPH1 was enhanced up to B-fold by unphosphorylated MBP and increasing ionic strength up to 0.2 M Nacl, whereas trypsinized preparations of PTPH1 containing the isolated catalytic domain were unaffected. These results suggest that in addition to a potential role in controlling subcellular localization, the NH2-terminal band 4.1 homology domain of PTPH1 may exert a direct effect on catalytic function.

Item Type: Paper
Uncontrolled Keywords: PHOSPHORYLATION IDENTIFICATION EZRIN EXPRESSION HOMOLOGY CLONING KINASES GENE
Subjects: bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > cytoskeletal proteins
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein characterization
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types
bioinformatics > genomics and proteomics > genetics & nucleic acid processing > protein structure, function, modification > protein types > enzymes > protein tyrosine phosphatase
CSHL Authors:
Communities: CSHL labs > Tonks lab
Depositing User: Matt Covey
Date: August 1995
Date Deposited: 17 Dec 2013 19:44
Last Modified: 17 Dec 2013 19:44
Related URLs:
URI: http://repository.cshl.edu/id/eprint/29055

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