Effects of protein kinase CK2, extracellular signal-regulated kinase 2, and protein phosphatase 2A on a phosphatidic acid-preferring phospholipase A1.
A soluble, phosphatidic acid-preferring phospholipase A1, expressed in mature bovine testes but not in newborn calf testes, may contribute to the formation or function of sperm. Here we incubated a recombinant preparation of the phospholipase in vitro with several enzymes including protein kinase CK2 (CK2), extracellular signal-regulated kinase 2 (ERK2), and protein phosphatase 2A (PP2A) to identify effects that might be of regulatory importance in vivo. Major findings were that 1) CK2 phosphorylated the phospholipase on serines 93, 105, and 716; 2) ERK2 phosphorylated the enzyme on serine 730; 3) there was cross-antagonism between the reactions that phosphorylated serines 716 and 730; 4) PP2A selectively hydrolyzed phosphate groups that were esterified to serines 716 and 730; 5) CK2alpha formed a stable, MgATP/MgGTP-dependent complex with the phospholipase by a novel mechanism; and 6) the complex showed reduced phospholipase activity and resembled a complex identified in homogenates of macaque testis. These results provide the first available information about the effects of reactions of phosphorylation and dephosphorylation on the behavior of the phospholipase, shed light on properties of CK2alpha that may be required for the formation of complexes with its substrates, and raise the possibility that a complex containing CK2alpha and the phospholipase may play a special biological role in the testis.
Han
M H
MH
Howard Hughes Medical Institute, Departments of Medicine and Biochemistry, and Regional Primate Research Center, University of Washington, Seattle, Washington 98195-7370, USA.
Han
D K
DK
Aebersold
R H
RH
Glomset
J A
JA
D000595:Amino Acid Sequence; D000818:Animals; D047390:Casein Kinase II; D002850:Chromatography, Gel; D008251:Macaca; D008297:Male; D013058:Mass Spectrometry; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D008969:Molecular Sequence Data; D010712:Phosphatidic Acids / Q000378:metabolism*; D010741:Phospholipases A / Q000737:chemistry / Q000378:metabolism*; D054466:Phospholipases A1; D010749:Phosphoprotein Phosphatases / Q000378:metabolism*; D010766:Phosphorylation; D011233:Precipitin Tests; D011485:Protein Binding; D054648:Protein Phosphatase 2; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D013737:Testis / Q000201:enzymology
D010712:Phosphatidic Acids; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D010741:Phospholipases A; D054466:Phospholipases A1; D010749:Phosphoprotein Phosphatases; D054648:Protein Phosphatase 2