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, but not by glucose, maltose, sucrose or galactose. Covalently-linked GPI-modified cell wall protein (GPI-CWP). 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). For many industrial applications in which the yeast S.cerevisiae is used, e.g. beer, wine and alcohol production, appropriate flocculation behavior is one of the most important characteristics of a good production strain. The ability of yeast cells to flocculate is of considerable importance, as it provides an effective, environment-friendly, simple and cost-free way to separate yeast cells from the fermentation product at the end of fermentation. Belongs to the flocculin family.