Title: | The Cdc42 GTPase-associated proteins Gic1 and Gic2 are required for polarized cell growth in Saccharomyces cerevisiae |
Author(s): | Chen GC; Kim YJ; Chan CS; |
Address: | "Department of Microbiology, The University of Texas, Austin, Texas 78712, USA" |
ISSN/ISBN: | 0890-9369 (Print) 0890-9369 (Linking) |
Abstract: | "BEM2 of Saccharomyces cerevisiae encodes a Rho-type GTPase-activating protein that is required for proper bud site selection at 26 degrees C and for bud emergence at elevated temperatures. We show here that the temperature-sensitive growth phenotype of bem2 mutant cells can be suppressed by increased dosage of the GIC1 gene. The Gic1 protein, together with its structural homolog Gic2, are required for cell size and shape control, bud site selection, bud emergence, actin cytoskeletal organization, mitotic spindle orientation/positioning, and mating projection formation in response to mating pheromone. Each protein contains a CRIB (Cdc42/Rac-interactive binding) motif and each interacts in the two-hybrid assay with the GTP-bound form of the Rho-type Cdc42 GTPase, a key regulator of polarized growth in yeast. The CRIB motif of Gic1 and the effector domain of Cdc42 are required for this association. Genetic experiments indicate that Gic1 and Gic2 play positive roles in the Cdc42 signal transduction pathway, probably as effectors of Cdc42. Subcellular localization studies with a functional green fluorescent protein-Gic1 fusion protein indicate that this protein is concentrated at the incipient bud site of unbudded cells, at the bud tip and mother-bud neck of budded cells, and at cortical sites on large-budded cells that may delimit future bud sites in the two progeny cells. The ability of Gic1 to associate with Cdc42 is important for its function but is apparently not essential for its subcellular localization" |
Keywords: | "Adaptor Proteins, Signal Transducing Amino Acid Sequence Binding Sites Carrier Proteins/*physiology Cell Compartmentation Cell Cycle Proteins/*physiology Cell Division Cell Survival Fungal Proteins/*physiology GTP-Binding Proteins/*physiology *GTPase-Acti;" |
Notes: | "MedlineChen, G C Kim, Y J Chan, C S eng GM45185/GM/NIGMS NIH HHS/ Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, P.H.S. 1997/12/31 Genes Dev. 1997 Nov 15; 11(22):2958-71. doi: 10.1101/gad.11.22.2958" |