Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-21280
J Cell Biol 1994 May 01;1254:705-19.
Show Gene links Show Anatomy links

Evidence for a dual role for TC4 protein in regulating nuclear structure and cell cycle progression.

Kornbluth S , Dasso M , Newport J .


???displayArticle.abstract???
TC4, a ras-like G protein, has been implicated in the feedback pathway linking the onset of mitosis to the completion of DNA replication. In this report we find distinct roles for TC4 in both nuclear assembly and cell cycle progression. Mutant and wild-type forms of TC4 were added to Xenopus egg extracts capable of assembling nuclei around chromatin templates in vitro. We found that a mutant TC4 protein defective in GTP binding (GDP-bound form) suppressed nuclear growth and prevented DNA replication. Nuclear transport under these conditions approximated normal levels. In a separate set of experiments using a cell-free extract of Xenopus eggs that cycles between S and M phases, the GDP-bound form of TC4 had dramatic effects, blocking entry into mitosis even in the complete absence of nuclei. The effect of this mutant TC4 protein on cell cycle progression is mediated by phosphorylation of p34cdc2 on tyrosine and threonine residues, negatively regulating cdc2 kinase activity. Therefore, we provide direct biochemical evidence for a role of TC4 in both maintaining nuclear structure and in the signaling pathways that regulate entry into mitosis.

???displayArticle.pubmedLink??? 8188741
???displayArticle.pmcLink??? PMC2120068

???displayArticle.grants??? [+]

Species referenced: Xenopus
Genes referenced: cdk1 ran

References [+] :
Arion, cdc2 is a component of the M phase-specific histone H1 kinase: evidence for identity with MPF. 1988, Pubmed, Xenbase