Together with PIL1, main component of eisosomes, structures at the cell periphery underneath the plasma membrane that mark the site of endocytosis. Negative regulator of cell wall integrity (CWI) in unstressed cells, probably by inhibiting protein kinase PKH1/PHK2 activity and regulating their downstream CWI pathways PKC1-MAP kinase pathway and protein kinase YPK1 pathway. Activity may be regulated by the transient increase of sphingolipid long chain bases (LCBs) during heat stress. Localizes at eisosomes, structures which colocalize with sites of protein and lipid endocytosis. Phosphorylated by PKH1 and PKH2. Phosphorylation is stimulated by sphingolipid long chain bases (LCBs). N-glycosylated. Present with 104485 molecules/cell in log phase SD medium.