p21-activated protein kinase gamma-PAK in pituitary secretory granules phosphorylates prolactin.
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.
Tuazon
Polygena T
PT
Department of Biochemistry, University of California at Riverside, 92521, USA.
Lorenson
Mary Y
MY
Walker
Ameae M
AM
Traugh
Jolinda A
JA
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
D006657:Histones; D011994:Recombinant Proteins; D011388:Prolactin; C515907:PAK2 protein, human; C515910:Pak2 protein, rat; D017346:Protein Serine-Threonine Kinases; D054462:p21-Activated Kinases