Abstract
p21-activated protein kinase gamma-PAK phosphorylates prolactin (PRL) in rat pituitary secretory granules on Ser-177 and on the equivalent site, Ser-179, in recombinant human PRL. This is shown by comparison of phosphopeptide maps with the human PRL mutant S179D. gamma-PAK is present in rat and bovine granules as identified by in-gel phosphorylation of histone H4, and by immunoblotting. Thus, phosphorylation of PRL by gamma-PAK in granules produces the PRL molecule that has been shown to antagonize the growth-promoting activity of unmodified PRL, and is consistent with the identified role of gamma-PAK in the induction and maintenance of cytostasis.
Publication types
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Animals
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Cattle
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Electrophoresis, Polyacrylamide Gel
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Histones / chemistry
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Histones / metabolism
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Humans
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Immunoblotting
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Molecular Weight
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Peptide Mapping
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Phosphorylation
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Pituitary Gland / chemistry
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Pituitary Gland / metabolism*
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Prolactin / chemistry*
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Prolactin / metabolism*
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Protein Serine-Threonine Kinases / analysis
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Protein Serine-Threonine Kinases / metabolism*
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Rats
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Recombinant Proteins / metabolism
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Secretory Vesicles / chemistry
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Secretory Vesicles / metabolism*
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p21-Activated Kinases
Substances
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Histones
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Recombinant Proteins
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Prolactin
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PAK2 protein, human
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Pak2 protein, rat
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Protein Serine-Threonine Kinases
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p21-Activated Kinases