Component of the outer cell wall layer. Required for stability of the cell wall and for optimal growth. Required for resistance against several antifungal and cell wall-perturbing agents and for tolerance to heat shock (By similarity). Covalently attached to the cell wall. The PIR1/2/3 repeats are required for the covalent linkage to the cell wall (By similarity). Their number varies among different strains of S.cerevisiae. Covalently linked to beta-1,3-glucan of the inner cell wall layer via an alkali-sensitive ester linkage between the gamma-carboxyl group of glutamic acids, arising from specific glutamines within the PIR1/2/3 repeats, and hydroxyl groups of glucoses of beta-1,3-glucan chains. The propeptide is cleaved off in the late Golgi. While both peptides are secreted, only a fraction of the mature glycoprotein is incorporated into the cell wall (By similarity). O-glycosylated. Extensively O-mannosylated (By similarity). Belongs to the PIR protein family.