Characterization of the phosphotyrosyl protein phosphatase activity of calmodulin-dependent protein phosphatase.

Download item | Update item information
Publication Type Journal Article
School or College College of Pharmacy; School of Medicine
Department Biomedical Informatics; Biochemistry; Pharmacology & Toxicology
Creator Blumenthal, Donald K.
Other Author Chan, Christine P.; Gallis, Byron; Pallen, Catherine J.; Wang, Jerry H.; Krebs, Edwin G.
Title Characterization of the phosphotyrosyl protein phosphatase activity of calmodulin-dependent protein phosphatase.
Date 1986-07-25
Description Calmodulin-dependent protein phosphatase from bovine brain and heart was assayed for phosphotyrosine and phosphoserine phosphatase activity using several substrates: 1) smooth muscle myosin light chain (LC20) phosphorylated on tyrosine or serine residues, 2) angiotensin I phosphorylated on tyrosine, and 3) synthetic phosphotyrosine- or phosphoserine-containing peptides with amino acid sequences patterned after the autophosphorylation site in Type II regulatory subunit of the cAMP-dependent protein kinase. The phosphatase was activated by Ni2+ and Mn2+, and stimulated further by calmodulin. In the presence of Ni2+ and calmodulin, it exhibited similar kinetic constants for the dephosphorylation of phosphotyrosyl LC20 (Km = 0.9 microM, and Vmax = 350 nmol/min/mg) and phosphoseryl LC20 (Km = 2.6 microM, Vmax = 690 nmol/min/mg). Dephosphorylation of phosphotyrosyl LC20 was inhibited by phosphoseryl LC20 with an apparent Ki of 2 microM. Compared to the reactions with phosphotyrosyl LC20 as the substrate, reactions with phosphotyrosine-containing oligopeptides exhibited slightly higher Km and lower Vmax values. The reaction with the phosphoseryl peptide based on the Type II regulatory subunit sequence exhibited a slightly higher Km (23 microM), but a much higher Vmax (4400 nmol/min/mg) than that with its phosphotyrosine-containing counterpart. Micromolar concentrations of Zn2+ inhibited the phosphatase activity; vanadate was less potent, and 25 mM NaF was ineffective. The study provides quantitative data to serve as a basis for comparing the ability of the calmodulin-dependent protein phosphatase to act on phosphotyrosine- and phosphoserine-containing substrates.
Type Text
Publisher American Society for Biochemistry and Molecular Biology (ASBMB)
Volume 261
Issue 21
First Page 9890
Last Page 9895
Subject Metabolism; Phosphatase Activity
Subject MESH Calmodulin; Fluorides; Kinetics; Manganese; Myocardium; Myosins; Nickel; Phosphoprotein Phosphatase; Phosphoric Monoester Hydrolases; Protein-Tyrosine-Phosphatase; Serine; Tyrosine; Vanadium; Zinc
Language eng
Bibliographic Citation Chan CP, Gallis B, Blumenthal DK, Pallen CJ, Wang JH, Krebs EG. Characterization of the phosphotyrosyl protein phosphatase activity of calmodulin-dependent protein phosphatase. J Biol Chem. 1986 Jul 25;261(21):9890-5. Retrieved August 31, 2006 from http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=2426255&query_hl=14&itool=pubmed_docsum
Rights Management Copyright © American Society for Biochemistry and Molecular Biology, J Biol Chem., 261, 9890-9895, 1986.
Format Medium application/pdf
Identifier ir-main,363
ARK ark:/87278/s6zw24ch
Setname ir_uspace
Date Created 2012-06-13
Date Modified 2012-06-13
ID 705928
Reference URL https://collections.lib.utah.edu/ark:/87278/s6zw24ch
Back to Search Results