ABSTRACT
Cell surface protein trafficking is regulated in response to nutrient availability, with multiple pathways directing surface membrane proteins to the lysosome for degradation in response to suboptimal extracellular nutrients. Internalised protein and lipid cargoes recycle back to the surface efficiently in glucose replete conditions, but this trafficking is attenuated following glucose starvation. We find cells with either reduced or hyperactive phosphatidylinositol 3-kinase activity are defective for recycling. Furthermore, we find the yeast Gα subunit Gpa1, which localises to endosomes and functionally couples with phosphatidylinositol 3-kinase, is required for surface recycling of cargoes. Following glucose starvation, nuclear translocation of Mig1 increases GPA2 levels and inhibits recycling, potentially by diverting Gpa1 to the surface and interfering with its endosomal role in recycling. Glucose privation therefore triggers a survival mechanism to increase retention of surface cargoes in endosomes and promote their lysosomal degradation.
Competing Interest Statement
The authors have declared no competing interest.