17 - MIC170 5/28/09 Lecture 17 (Thursday, 5/28) Continued...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: MIC170 5/28/09 Lecture 17 (Thursday, 5/28) Continued on Cell cycle control Additional Regulatory factors at the G2/M transition --- Wee1 and Cdc25 1. wee1ts mutant in fission yeast ----- discussed in the last lecture 2. cdc25ts mutant (Fig. 4-5 in handout-9) ----> at 37oC, cells arrest in G2 and cannot initiate mitosis, like cdc2ts cdc25+ gene was cloned similarity to protein phosphatase multicopy of cdc25+ gene -- advanced mitosis (wee phenotype) (Fig. 4-9 in handout 9) Thus, Cdc25 is a positive regulator of mitotic initiation. Relationship between cdc25 and cdc2? cdc2-3w cdc25 double mutant ----- similar to the cdc2-3w single mutant (divide at ~8 m) cdc2-3w carrying multicopy cdc25+ ----- similar to cdc2-3w Cdc25 positively functions upstream of Cdc2 Cdc25 Cdc2 G2 M 1 MIC170 5/28/09 Relationship between wee1 and cdc25? cdc25 wee1 double mutant ----- divide at normal cell length (Fig. 4-5, handout 9; double mutant phenotype is different from those of the single mutants) Cdc25 and Wee1 independently regulate Cdc2 Cdc25 Wee1 Cdc2 G2 M Subsequent biochemical studies demonstrated that the Wee1 kinase inhibits Cdc2 by direct phosphorylation of Tyr-15 in Cdc2. At the end of the G2 phase, this inhibitory phosphorylation on Cdc2 is removed by the Cdc25 phosphatase, so that the activated Cdc2-cyclin complex can induce mitosis. Wee1 and Cdc25 are also conserved in human cells and regulate Cdc2 (CDK) at the entry into mitosis. 2 ...
View Full Document

This note was uploaded on 06/11/2009 for the course MIC 170 taught by Professor Shiozaki during the Spring '09 term at UC Davis.

Ask a homework question - tutors are online