Functional and genetic study of yeast ADP-ribosylation factor 3

• Main Authors: Szu-Wei Lee, 李思緯
• Other Authors: 李芳仁
• Format: Others
• Language: en_US
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/55095210697182167504

碩士 === 國立臺灣大學 === 分子醫學研究所 === 93 === ADP-ribosylation factors (ARFs) are highly conserved small GTP-binding proteins and are critical components of vesicular trafficking in eukaryotic cells. Yeast Arf3p, in spite of its similarity to mammalian homologue ARF6, is not required for fluid-phase, membrane internalization or mating-type receptor-mediated endocytosis; instead, it is involved in polarity development. To further explore the biological functions of Arf3p, functional and genetic studies were adopted. Bud2p, which was reported to show an interaction with Arf3p in large-scale yeast two-hybrid analysis, specifically interacts with Arf3p in a GTP-dependent manner in vivo. The subcellular localization of Bud2p is not affected by ARF3 disruption, and vice versa. However, nonpolarized overexpressed Arf3p and Arf3Q71L are concentrated at the mother-bud junction by polarized overexpressed Bud2p, indicating that Bud2p also interacts with Arf3p in living cells. Although BUD2 encodes a GAP for Bud1p, it may not be a GAP for Arf3p. BUD2 disruption as well as ARF3 disruption exhibits early actin patch depolarization at higher temperatures, and combination of arf3 and bud2 deletions does not exacerbate the phenotype, implying that Bud2p and Arf3p contribute a role in the same pathway indirectly regulating actin cytoskeleton organization. Moreover, neither Arf3p nor Bud2p is required for Snc1p and Chs3p trafficking. The precise relationship between Bud2p and Arf3p remains to be elucidated. Besides, an interaction between Arf3p and the endocytic machinery, in which Lsb5p and Ysc84p were shown to be together involved, needs to be determined.