Yeast Pmp3p has an important role in plasma membrane organization.

Pmp3p-related proteins are highly conserved proteins that exist in bacteria, yeast, nematodes, and plants, whose transcript is regulated in response to abiotic stress such as low temperature or high salinity. Pmp3p was originally identified in S. cerevisiae where it belongs to the SNA (Sensitive to Na + ) protein family which is composed of four members: Pmp3p/Sna1p, Sna2p, Sna3p, and Sna4p. Deletion of the PMP3 gene confers sensitivity to cytotoxic cations, while removal of the other SNA genes did not lead to clear phenotypic effects. It was long believed that Pmp3p-related proteins may have a common and important role in the modulation of plasma membrane potential and in the regulation of intracellular ion homeostasis. Here we show that several growth phenotypes linked to PMP3 deletion can be modulated by the removal of specific genes involved in sphingolipid synthesis. These genetic interactions, together with lipid binding assays and epifluorescence microscopy, as well as other biochemical experiments, suggest that Pmp3p could be part of a phosphoinositide-regulated stress sensor.