Cell wall protein that participates directly in adhesive cell-cell interactions during yeast flocculation, a reversible, asexual and Ca(2+)-dependent process in which cells adhere to form aggregates (flocs) consisting of thousands of cells. The lectin-like protein sticks out of the cell wall of flocculent cells and selectively binds mannose residues in the cell walls of adjacent cells. Activity is inhibited by mannose, glucose, maltose and sucrose. Also involved in cell-substrate adhesion, haploid invasive growth and diploid pseudohyphae formation. The number of the intragenic tandem repeats varies between different S.cerevisiae strains. There is a linear correlation between protein size and the extend of adhesion: the more repeats, the stronger the adhesion properties and the greater the fraction of flocculating cells (By similarity). 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 (By similarity). Belongs to the flocculin family.