Document Type
Article
Publication Date
2-2-2005
Publication Title
Molecular Biology of the Cell
Department
Geisel School of Medicine
Abstract
The Rab GTPase Ypt1p and the large homodimer Uso1p are both required for tethering endoplasmic reticulum-derived vesicles to early Golgi compartments in yeast. Loss-of-function ypt1 and uso1 mutations are suppressed by SLY1-20, a dominant allele that encodes the Sed5p-associated protein, Sly1p. Here, we investigate the mechanism of SLY1-20 suppression. In wild-type strains, Ypt1p can be coimmunoprecipitated with Uso1p; however, in a ypt1Δ/SLY1-20 strain, which lacks this complex, membrane binding of Uso1p was reduced. In spite of Ypt1p depletion, Uso1p-dependent vesicle tethering was not bypassed under the ypt1Δ/SLY1-20 condition. Moreover, tethering and fusion assays with ypt1Δ/SLY1-20 membranes remained sensitive to Rab GDP dissociation inhibitor. These results indicate that an alternative Rab protein satisfies the Ypt1p requirement in Uso1p-dependent tethering when SLY1-20 is expressed. Further genetic and biochemical tests revealed that a related Rab protein, Ypt6, might substitute for Ypt1p in ypt1Δ/SLY1-20 cells. Additional experimentation to address the mechanism of SLY1-20 suppression in a cog2Δ [sec35Δ] strain indicated that the Cog2p subunit of the conserved oligomeric Golgi complex is either functionally redundant or is not directly required for anterograde transport to the Golgi complex.
DOI
10.1091/mbc.E04-08-0725
Original Citation
Ballew N, Liu Y, Barlowe C. A Rab requirement is not bypassed in SLY1-20 suppression. Mol Biol Cell. 2005 Apr;16(4):1839-49. doi: 10.1091/mbc.e04-08-0725. Epub 2005 Feb 2. PMID: 15689495; PMCID: PMC1073665.
Dartmouth Digital Commons Citation
Ballew, Nicole; Liu, Yiting; and Barlowe, Charles, "A Rab Requirement is Not Bypassed in SLY1-20 Suppression" (2005). Dartmouth Scholarship. 3771.
https://digitalcommons.dartmouth.edu/facoa/3771
