Tk. Kwon et al., THE DIFFERENTIAL CATALYTIC ACTIVITY OF ALTERNATIVELY SPLICED CDK2-ALPHA AND CDK2-BETA IN THE G(1) S TRANSITION AND EARLY S-PHASE/, Experimental cell research, 238(1), 1998, pp. 128-135
Progression through the G(1)/S transition of the cell cycle is regulat
ed by cyclin E/cdk2 and cyclin A/cdk2 complexes, We demonstrate that t
here are two forms of murine cdk2, (cdk2 alpha and beta), Cdk2 alpha c
onsist of 298 amino acids, while cdk2 beta contains a 48-amino-acid in
sert between Met (196) and Val (197) of cdk2 alpha, Cdk2 beta results
from differential splicing of the primary RNA transcript of the cdk2 g
ene. Although human cdk2 genomic DNA contained the sequence of the ins
ert for the beta form, cdk2 beta was not detected by either Western bl
ot or RT-PCR in human T-cells or several other human cell lines, Cdk2
beta expression in murine cells was similar to that of the phosphoryla
ted, catalytically active form of cdk2 alpha. Cdk2 alpha and cdk2 beta
have very similar binding activity to cyclin E and to the cdk inhibit
or p27(KipI), The alternatively spliced cdk2 beta possesses catalytic
activity in vivo and in vitro, The differential catalytic activity of
these two forms of cdk2, suggests that cdk2 alpha and cdk2 beta may pe
rform different functions at or near the G(1)/S transition and early S
phase. (C) 1998 Academic Press.