ABSTRACT
We identified the ORF YBR264c during the systematic sequencing of the Saccharomyces cerevisiae genome. It encodes a putative protein of 218 amino acids. We demonstrate here that the gene is indeed expressed and encodes a new Ypt in yeast. This protein specifically binds guanine nucleotides and interacts via its C-terminal end with the unique Rab GDP Dissociation Inhibitor (RabGDI). In accordance with a recent proposal, the gene is now designated YPT10. No mutant phenotype could be associated with inactivation of the gene. However, overexpression of YPT10 resulted in defects in growth; microscopic examination of such cells revealed an overabundance of vesicular and tubular structures, suggesting some alteration in the function of the Golgi apparatus. In addition, degradation of the Ypt10 protein, which possesses a PEST sequence, is shown to be dependent on proteasome activity.
Subject(s)
Cysteine Endopeptidases/metabolism , GTP Phosphohydrolases/genetics , GTP-Binding Proteins/genetics , GTP-Binding Proteins/metabolism , Guanine Nucleotide Dissociation Inhibitors , Multienzyme Complexes/metabolism , Open Reading Frames , Saccharomyces cerevisiae Proteins , Saccharomyces cerevisiae/genetics , Amino Acid Sequence , GTP Phosphohydrolases/metabolism , GTP-Binding Proteins/chemistry , Genotype , Guanosine Triphosphate/metabolism , Molecular Sequence Data , Proteasome Endopeptidase Complex , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae/ultrastructure , Sequence Alignment , Sequence Homology, Amino AcidABSTRACT
We identified the ORF YBR260c during systematic sequencing of one region of chromosome II of Saccharomyces cerevisiae. This ORF encodes a putative protein of 666 aa, of which the C-terminal part of the deduced amino acid sequence resembles human and yeast Rho/Rac GTPase activating proteins (GAP). An initial study is reported in the paper. This gene was expressed in haploid and diploid cells and was called RGD1 for related GAP domain 1. Inactivation of RGD1 was carried out and phenotypic analysis of the mutant strain revealed only a slight viability defect when cells grown in minimal medium were close to stationary phase. Northern and western analyses showed that the RGD1 transcript and the corresponding protein were still abundant in cells cultivated in YNB during the stationary phase. No functional link seems to exist with the highly conserved GTPase Cdc42 involved in cytoskeletal polarization and cell polarity.