Required for proper cell wall integrity and for the correct assembly of the mannoprotein outer layer of the cell wall. Identified as GPI-anchored plasma membrane protein (GPI-PMP) as well as covalently-linked GPI-modified cell wall protein (GPI-CWP) in the outer cell wall layer. The GPI-anchor is attached to the protein in the endoplasmic reticulum and serves to target the protein to the cell surface. There, the glucosamine-inositol phospholipid moiety is cleaved off and the GPI-modified mannoprotein is covalently attached via its lipidless GPI glycan remnant to the 1,6-beta-glucan of the outer cell wall layer. Belongs to the SPS2 family.