title: p21-activated protein kinase gamma-PAK in pituitary secretory granules phosphorylates prolactin.
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.
authors.affiliation: Department of Biochemistry, University of California at Riverside, 92521, USA.
authors.forename: Polygena T
authors.initials: PT
authors.lastname: Tuazon
authors.forename: Mary Y
authors.initials: MY
authors.lastname: Lorenson
authors.forename: Ameae M
authors.initials: AM
authors.lastname: Walker
authors.forename: Jolinda A
authors.initials: JA
authors.lastname: Traugh
mesh_terms: D000818:Animals; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D015151:Immunoblotting; D008970:Molecular Weight; D010449:Peptide Mapping; D010766:Phosphorylation; D010902:Pituitary Gland / Q000737:chemistry / Q000378:metabolism*; D011388:Prolactin / Q000737:chemistry* / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism*; D051381:Rats; D011994:Recombinant Proteins / Q000378:metabolism; D022142:Secretory Vesicles / Q000737:chemistry / Q000378:metabolism*; D054462:p21-Activated Kinases
chemical_list: D006657:Histones; D011994:Recombinant Proteins; D011388:Prolactin; C515907:PAK2 protein, human; C515910:Pak2 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases