Isolation and partial characterization of an Mr 60,000 subunit of a type 2A phosphatase from rabbit reticulocytes.
A Mr 60,000 peptide that modulates the activity of the Mr 35,000 catalytic subunit of a type 2A phosphatase has been isolated from rabbit reticulocytes and partially characterized. The peptide appears to be a subunit of the intact phosphatase that has been isolated under nondenaturing conditions. The Mr 60,000 peptide itself is catalytically inactive. However, it binds to the Mr 35,000 catalytic subunit causing a decrease in its activity for dephosphorylation of phosphorylated 40 S ribosomal subunits, but an increase in dephosphorylation of peptide initiation factor 2 phosphorylated in its alpha subunit. Reassociation of the Mr 60,000 and the Mr 35,000 peptides yields a two-subunit phosphatase with a Stokes radius of 42 A; sedimentation coefficient, S20,w of 5.1 S; molecular weight of 89,000. These parameters are compared to those of the native three-subunit enzyme and those of the isolated Mr 35,000 and 60,000 peptides.
Chen
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SC
Clayton Foundation Biochemical Institute, Department of Chemistry, University of Texas, Austin 78712.
Kramer
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G
Hardesty
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B
D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D015852:Eukaryotic Initiation Factor-2; D006358:Hot Temperature; D007700:Kinetics; D046911:Macromolecular Substances; D008345:Manganese / Q000502:physiology; D008970:Molecular Weight; D010448:Peptide Initiation Factors / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000097:blood* / Q000276:immunology; D011506:Proteins / Q000378:metabolism; D011817:Rabbits; D012156:Reticulocytes / Q000201:enzymology*; D012269:Ribosomal Proteins / Q000378:metabolism; D013379:Substrate Specificity
D000911:Antibodies, Monoclonal; D015852:Eukaryotic Initiation Factor-2; D046911:Macromolecular Substances; D010448:Peptide Initiation Factors; D011506:Proteins; D012269:Ribosomal Proteins; D008345:Manganese; D010749:Phosphoprotein Phosphatases