The retinoblastoma protein physically associates with the human cdc2 kinase.
The protein product (pRB) of the retinoblastoma susceptibility gene functions as a negative regulator of cell proliferation, and its activity appears to be modulated by phosphorylation. Using a new panel of anti-human pRB monoclonal antibodies, we have investigated the biochemical properties of this protein. These antibodies have allowed us to detect a pRB-associated kinase that has been identified as the cell cycle-regulating kinase p34cdc2 or a closely related enzyme. Since this associated kinase phosphorylates pRB at most of the sites used in vivo, these results suggest that this kinase is one of the major regulators of pRB. The associated kinase activity follows the pattern of phosphorylation seen for pRB in vivo. The associated kinase activity is not seen in the G1 phase but appears in the S phase, and the levels continue to increase throughout the remainder of the cell cycle.
Hu
Q J
QJ
Cold Spring Harbor Laboratory, New York 11724.
Lees
J A
JA
Buchkovich
K J
KJ
Harlow
E
E
D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D016203:CDC2 Protein Kinase / Q000378:metabolism*; D002455:Cell Division; D002478:Cells, Cultured; D015180:Electrophoresis, Gel, Two-Dimensional; D006801:Humans; D010449:Peptide Mapping; D010766:Phosphorylation; D011233:Precipitin Tests; D016160:Retinoblastoma Protein / Q000276:immunology / Q000378:metabolism*; D013379:Substrate Specificity
D000911:Antibodies, Monoclonal; D016160:Retinoblastoma Protein; D016203:CDC2 Protein Kinase