Shs1p: a novel member of septin that interacts with spa2p, involved in polarized growth in saccharomyces cerevisiae.

The Rho family small G proteins regulate various cell functions including cytokinesis. We have shown that Bni1p, a potential target of Rho1p, interacts with Spa2p and that Spa2p is required for the localization of Bni1p at the growth sites in Saccharomyces cerevisiae. We isolated here a novel member of the septin family, implicated in cytokinesis, as a Spa2p-binding protein by the yeast two-hybrid method. We named this gene SHS1 (Seventh Homolog of Septin). The shs1 mutant cells showed cytokinesis deficiency and Shs1p was localized at the bud neck in budded cells. The Spa2p-Shs1p interactions may play an important role in cytokinesis.