High impact information on BUD6

• The membrane-associated protein Bud6 localized to the bud neck in a septin-dependent manner and was required to restrict the diffusion of ER membrane proteins [1].
• Together, these results demonstrate Bud6p function in MT capture at the cell cortex, independent of Kar9p-mediated MT delivery along actin cables [2].
• Bud6p function has been linked to Kar9p, a protein guiding MTs along actin cables [2].
• Moreover, additive phenotypes in bud6Delta kar9Delta or bud6Delta dyn1Delta mutants underscored the separate contributions of Bud6p, Kar9p, and dynein to spindle positioning [2].
• This program requires Bud6p/Aip3p to direct the old pole to the bud and confine the new pole to the mother cell [2].

Biological context of BUD6

• By using the two-hybrid system, Spa2p and Bud6p were also found to interact with components of two mitogen-activated protein kinase (MAPK) pathways important for polarized cell growth [3].
• Aip3p/Bud6p, a yeast actin-interacting protein that is involved in morphogenesis and the selection of bipolar budding sites [4].
• MATa/alpha daughter cells lacking Aip3p place their first buds normally at their distal poles but choose random sites for budding in subsequent cell cycles [4].
• When expressed in budding yeast, spAip3p localizes similarly to Aip3p during the cell cycle and complements the cell polarity defects of an aip3Delta strain [5].
• These differences are mediated by the relative partition of Bud6 between the bud tip and bud neck, distinguishing haploids from diploids [6].

Anatomical context of BUD6

• Bud6p has been shown previously to interact with actin, suggesting that the 12S complex functions to regulate the actin cytoskeleton [3].
• Differential contribution of Bud6p and Kar9p to microtubule capture and spindle orientation in S. cerevisiae [2].
• These are the interactions selectively impaired at the bud cortex in bud6 delta cells [7].
• Biochemical data show that a pool of Aip3p is associated with post-Golgi secretory vesicles [8].

Physical interactions of BUD6

• Bud6p interacts with Ste11p [3].
• We mapped Bud6 binding activity to specific residues in the carboxyl terminus of Bni1 that are adjacent to its diaphanous autoregulatory domain (DAD) [9].
• To our knowledge, bud6p is the first protein shown to interact physically with tea1p [10].

Regulatory relationships of BUD6

• Thus, Bud6 differentially stimulates Bni1 and not Bnr1 [9].

Other interactions of BUD6

• We found that Bud6 is up-regulated during bud growth, when it is delivered to the bud tip on Bni1-nucleated actin cables [9].
• Differential activities and regulation of Saccharomyces cerevisiae formin proteins Bni1 and Bnr1 by Bud6 [9].
• Surprisingly, the localization of Aip3p does not appear to require either polarized actin or the septin proteins of the neck filaments [4].
• Bnr1p also directly interacted with Bud6p, a novel actin-binding protein [11].
• Here, we show that Kar9p does not mediate Bud6p functions in spindle orientation [2].

References