Figure 2.

A model PAS kinase activation and function in S. cerevisiae. Autoinhibited PAS kinase can be activated by either growth on nonfermentative carbon sources or by cell integrity stress. The activation of PAS kinase by nonfermenative carbon source requires the Snf1 protein and may involve the production of a regulatory metabolite (star), while the cell integrity stress pathway can be activated by a range of cell wall or cell membrane perturbing agents as well as by overexpression of Wsc1. Activated PAS kinase then phosphorylates Ugp1, which leads to increased cell wall glucan biosynthesis at the expense of glycogen biosynthesis.⁸