Abstract
We have generated site-directed mutants of the catalytic subunit of rabbit muscle ppase-1. Since it is known that ppase-1 and ppase-2A are highly susceptible to inactivation by sulfhydryl reagents, we have mutagenized the six cysteine residues conserved between these two enzymes to serines. The six mutants were purified to near homogeneity by affinity chromatography on inhibitor-2-Sepharose and characterized. All six exhibited enzymatic activity. These results indicate that the catalytic mechanism of ppase-1 is different from that of the protein tyrosine phosphatases which involve a cysteinyl phosphate intermediate.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Sequence
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Animals
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Base Sequence
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Binding Sites
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Chromatography, Affinity
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Cloning, Molecular
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DNA Primers
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Electrophoresis, Polyacrylamide Gel
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Enzyme Stability
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Hot Temperature
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Kinetics
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Molecular Sequence Data
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Muscles / enzymology*
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Mutagenesis, Site-Directed
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Phosphoprotein Phosphatases / chemistry
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Phosphoprotein Phosphatases / isolation & purification
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Phosphoprotein Phosphatases / metabolism*
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Protein Phosphatase 1
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Rabbits
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Recombinant Proteins / chemistry
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Recombinant Proteins / isolation & purification
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Recombinant Proteins / metabolism
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Thermodynamics
Substances
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DNA Primers
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Recombinant Proteins
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Phosphoprotein Phosphatases
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Protein Phosphatase 1