Phosphorylation of the translational regulator, PHAS-I, by protein kinase CK2.
The primary site in PHAS-I for phosphorylation by protein kinase CK2 in vitro was identified as Ser111. A relatively small amount of phosphorylation of Ser99 was also detected, and mutating Ser99 to Ala in PHAS-I slightly decreased phosphorylation by CK2 in vitro. In contrast, mutating Ser111 to Ala almost abolished phosphorylation, confirming Ser111 as the preferred site for CK2. Phosphorylation of Ser111 did not decrease binding of PHAS-I to eIF4E, and results of peptide mapping experiments with PHAS-I immunoprecipitated from 32P-labeled adipocytes indicated that Ser111 was not phosphorylated in cells. These results support the conclusion that CK2 is not involved in the control of PHAS-I.
Department of Pharmacology, University of Virginia School of Medicine, Health Sciences Center, Charlottesville 22908, USA.
P
P
Fadden
T A
TA
Haystead
J C
JC
Lawrence
D017667:Adipocytes / Q000201:enzymology / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins; D047390:Casein Kinase II; D039561:Eukaryotic Initiation Factor-4E; D047908:Intracellular Signaling Peptides and Proteins; D008297:Male; D010448:Peptide Initiation Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D012694:Serine / Q000378:metabolism
D002352:Carrier Proteins; C499526:Eif4ebp1 protein, rat; D039561:Eukaryotic Initiation Factor-4E; D047908:Intracellular Signaling Peptides and Proteins; D010448:Peptide Initiation Factors; D010750:Phosphoproteins; D012694:Serine; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases