Linking Ras to Myosin Function: RasGEF Q, a Dictyostelium Exchange Factor for RasB, Affects Myosin II Functions

Overview

Journal J Cell Biol

Specialty Cell Biology

Date 2008 May 28

PMID 18504297

Citations 14

Authors

Subhanjan Mondal

Deenadayalan Bakthavatsalam

Paul Steimle

Berthold Gassen

Francisco Rivero

Angelika A Noegel

Affiliations

Soon will be listed here.

Abstract

Ras guanine nucleotide exchange factor (GEF) Q, a nucleotide exchange factor from Dictyostelium discoideum, is a 143-kD protein containing RasGEF domains and a DEP domain. We show that RasGEF Q can bind to F-actin, has the potential to form complexes with myosin heavy chain kinase (MHCK) A that contain active RasB, and is the predominant exchange factor for RasB. Overexpression of the RasGEF Q GEF domain activates RasB, causes enhanced recruitment of MHCK A to the cortex, and leads to cytokinesis defects in suspension, phenocopying cells expressing constitutively active RasB, and myosin-null mutants. RasGEF Q(-) mutants have defects in cell sorting and slug migration during later stages of development, in addition to cell polarity defects. Furthermore, RasGEF Q(-) mutants have increased levels of unphosphorylated myosin II, resulting in myosin II overassembly. Collectively, our results suggest that starvation signals through RasGEF Q to activate RasB, which then regulates processes requiring myosin II.

Citing Articles

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