ik3-1/Cables is a substrate for cyclin-dependent kinase 3 (cdk 3).
p70ik3-1 (a 70-kDa protein) contains a cyclin box, and binds to p35cdk3 in vivo and in vitro [Matsuoka, M., Matsuura, Y., Semba, K. & Nishimoto, I. (2000) Biochem. Biophys. Res. Commun. 273, 442-447]. In spite of its structural similarity to cyclins, p70ik3-1 does not activate cyclin-dependent kinase 3 (cdk3)-mediated phosphorylation of pRb, histone H1, or the C-terminal domain of RNA polymerase II. Here, we report that Ser274 of p70ik3-1 is phosphorylated by cdk2 or cdk3 bound to cyclin A and to cyclin E in vitro. We also found that in COS7 cells in which cyclin E and cdk3 were ectopically overexpressed, the phosphorylation level of Ser274 in coexpressed p70ik3-1 is upregulated. We therefore conclude that p70ik3-1 is a substrate for cdk3-mediated phosphorylation.
Yamochi
T
T
Department of Pharmacology, KEIO University School of Medicine, Tokyo, Japan.
Semba
K
K
Tsuji
K
K
Mizumoto
K
K
Sato
H
H
Matsuura
Y
Y
Nishimoto
I
I
Matsuoka
M
M
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D042846:CDC2-CDC28 Kinases; D019556:COS Cells; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019925:Cyclin A / Q000235:genetics / Q000378:metabolism; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism; D051357:Cyclin-Dependent Kinase 2; D056849:Cyclin-Dependent Kinase 3; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D016297:Mutagenesis, Site-Directed; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012694:Serine / Q000737:chemistry; D013379:Substrate Specificity; D014162:Transfection
C486568:CABLES1 protein, human; D002352:Carrier Proteins; D019925:Cyclin A; D019927:Cyclin E; D016213:Cyclins; D018076:DNA, Complementary; D010750:Phosphoproteins; D011994:Recombinant Proteins; D012694:Serine; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C098776:CDK3 protein, human; C490914:Cdk3 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D056849:Cyclin-Dependent Kinase 3; D018844:Cyclin-Dependent Kinases