Figure 6.

Regulation of yeast cell polarity by Cdc28p. Previous work has established antagonistic functions of Cln and Clb cyclins in morphogenesis. The polarization of cortical actin patches (black dots) and cell wall deposition to the nascent bud site at Start is Cln dependent, whereas the apical-isotropic switch leading to redistribution of actin and swelling growth of the bud in mitosis is Clb dependent. The results of this study suggest that the Cln cyclins may maintain polar growth and prevent the apical-isotropic switch by activating Swe1p, a tyrosine kinase that inhibits Clb-Cdc28p complexes.