Premium
A cell‐cycle‐regulated kinase activity phosphorylates plant retinoblastoma protein and contains, in Arabidopsis , a CDKA/cyclin D complex
Author(s) -
Boniotti Maria Beatrice,
Gutierrez Crisanto
Publication year - 2001
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.2001.01160.x
Subject(s) - microbiology and biotechnology , arabidopsis , cyclin dependent kinase , cyclin , cell cycle , kinase , retinoblastoma protein , cyclin dependent kinase 4 , protein kinase a , retinoblastoma , cyclin dependent kinase 3 , cyclin dependent kinase complex , cyclin dependent kinase 2 , chemistry , biology , cell , biochemistry , gene , mutant
Summary The activity of cyclin‐dependent kinases (CDK) is crucial for cell‐cycle transitions. Here, we report the identification of a CDK activity that phosphorylates the retinoblastoma‐related (RBR) protein. A CDK/cyclin complex that binds to and phosphorylates RBR may be isolated from various plant sources, e.g. wheat, maize, Arabidopsis thaliana and tobacco, and from cells growing under various conditions. The presence of an RBR‐associated CDK activity correlates with the proliferative activity, suggesting that phosphorylation of RBR is a major event in actively proliferating tissues. In A. thaliana , this activity comprises a PSTAIRE CDKA and at least cyclin D2. Furthermore, this CDK activity is cell‐cycle‐regulated, as revealed by studies with highly synchronized tobacco BY‐2 cells where it is maximal in late G1 and early S phase cells and progressively decreases until G2 phase. Aphidicolin‐arrested but not roscovitine‐arrested cells contain a PSTAIRE‐type CDK that binds to and phosphorylates RBR. Thus, association with a D‐type cyclin is a likely mechanism leading to CDK activation late in G1. Our studies constitute the first report measuring the activity of CDK/cyclin complexes formed in vivo on RBR, an activity that fluctuates in a cell‐cycle‐dependent manner. This work provides the basis for further studies on the impact of phosphorylation of RBR on its function during the cell cycle and development.