Pmp3 is an evolutionarily conserved proteolipid in the plasma membrane which, in S. pombe, is transcriptionally regulated by the Spc1 stress MAPK (mitogen-activated protein kinases) pathway. It functions to modulate the membrane potential, particularly to resist high cellular cation concentration. In eukaryotic organisms, stress-activated mitogen-activated protein kinases play crucial roles in transmitting environmental signals that will regulate gene expression for allowing the cell to adapt to cellular stress. Pmp3-like proteins are highly conserved in bacteria, yeast, nematode and plants.

1: The fission yeast stress MAPK cascade regulates the pmp3+ gene that encodes a highly conserved plasma membrane protein. Wang LY, Shiozaki K; FEBS Lett. 2006;580:2409-2413. PMID:16603158