Component of the cell wall. Identified as covalently-linked GPI-modified cell wall protein (GPI-CWP) as well as protein covalently linked via an alkali-sensitive bond not requiring the GPI-derived structure. Can also be double-anchored to the cell wall through both types of linkages. Incorporated into the birth scar of a daughter cell. Positively regulated by cell integrity signaling through MPK1 in response to cell wall perturbation. Induction is dependent on transcription factor RLM1. Down-regulated during anaerobic growth. Up-regulated by low pH. Extensively O-glycosylated. 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. 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 a specific glutamine within the PIR1/2/3 repeat, and hydroxyl groups of glucoses of beta-1,3-glucan chains (By similarity). The alkali-sensitive linkage is induced by low pH. The strains CLIB 410 and CLIB 630 haplotype Ha2, contain large deletions that remove most of the protein. Present with 67000 wall-bound molecules/cell in log phase YPD medium. Belongs to the SRP1/TIP1 family.