FIG. 8.

Proposed activation of the Rho1 module by Hcs77. Hcs77, a putative mechanosensor, may activate Tor2, a phosphatidylinositol kinase homolog. Tor2 is proposed to activate Rom2, a GEF for Rho1-GDP. Alternatively, Hcs77 could activate Rom2 directly or could inhibit Sac7, a GAP for Rho1-GTP. This inhibition would promote the Rho1-GTP state. Rho1-GTP activates Pkc1, glucan synthase, and presumably other substrates. Solid arrows indicate activation; dashed arrows are highly speculative. See the text for details.