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- Title
Linking Ras to myosin function: RasGEF Q, a Dictyostelium exchange factor for RasB, affects myosin II functions.
- Authors
Mondal, Subhanjan; Bakthavatsalam, Deenadayalan; Steimle, Paul; Gassen, Berthold; Rivero, Francisco; Noegel, Angelika A.
- 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[sup -] mutants have defects in cell sorting and slug migration during later stages of development, in addition to cell polarity defects. Furthermore, RasGEF Q[sup -] 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.
- Subjects
G proteins; MYOSIN; DICTYOSTELIUM; ACTIN; CYTOKINESIS
- Publication
Journal of Cell Biology, 2008, Vol 181, Issue 5, p747
- ISSN
0021-9525
- Publication type
Article
- DOI
10.1083/jcb.200710111