Pho81

Pho81 is a protein found in the yeast Saccharomyces cerevisiae. It is a component of the vacuolar membrane and plays a crucial role in the regulation of the vacuolar H+-ATPase (V-ATPase). The V-ATPase is a proton pump responsible for acidifying the vacuole, an organelle involved in various cellular processes including storage, degradation, and ion homeostasis.

Pho81 acts as an inhibitory subunit of the V-ATPase. When Pho81 is bound to the V-ATPase complex, it reduces the pump's activity. This regulation is important for maintaining proper vacuolar pH, which in turn affects numerous cellular functions. The activity of Pho81 is itself regulated by various signaling pathways, including those involved in phosphate homeostasis and cellular stress.

The interaction of Pho81 with the V-ATPase is a key mechanism for controlling vacuolar acidification in response to cellular needs. For instance, under conditions of phosphate starvation, Pho81's association with the V-ATPase may be altered, leading to changes in V-ATPase activity that can support cellular adaptation. Research into Pho81 continues to shed light on the complex regulatory mechanisms governing vacuolar function and its impact on overall yeast cell physiology.