QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

Cover  Asymmetry at the cellular level determines polarized growth, development, directed secretion, and subcellular organization. In the yeast Saccharomyces cerevisiae, asymmetry is determined in part by bud-site-selection proteins that mark specific sites in the cell to direct bud emergence. Distinct bud-site-selection proteins function in haploid and diploid cell types. We found that the Bud8p protein, which localizes to and directs distal-pole budding in diploid cells, is also required in haploid cells during filamentous growth. Bud8p localizes to the distal tip of haploid cells and, under glucose-limiting conditions, promotes distal-pole budding resulting in a filament of connected cells (top center panel). Loss of Bud8p prevents distal-pole budding in haploid cells, severely compromising filamentous growth (bottom center panel). Localization experiments (left and right panels) demonstrate that the cues, which mark proximal and distal poles in the haploid cell, are present under glucose-rich and glucose-limiting conditions. It is the disappearance of a haploid-specific protein, Ax11p, under glucose-limiting conditions that results in the use of the Bud8p distal-pole marker and filamentous growth in haploid yeast. For more information, see Cullen and Sprague "The Roles of Bud-Site-Selection Proteins during Haploid Invasive Growth in Yeast" (Mol. Biol. Cell [2002]. 13:2990-3004). Paul J. Cullen