Yeast Kre1p is a cell surface O-glycoprotein.

The Saccharomyces cerevisiae KRE1 gene encodes a secretory protein required for the production of the cell wall polymer (1-->6)-beta-glucan. Here we report further characterization of the KRE1 gene product, Kre1p. A functional, epitope-tagged Kre1p is shown to be highly modified in a SEC53-dependent manner. Kre1p is O-glycosylated, but the basis for the majority of its post-translational modification is unknown. Fractionation of Kre1p reveals a cell wall-associated form and a less abundant membrane-associated species. Indirect immunoflurorescence demonstrates that Kre1p localizes to the cell surface, where it becomes concentrated at the surface of mother cells. Such a localization of Kre1p seems to parallel the CAL1/CSD2-dependent cell wall deposition of chitin found in S. cerevisiae, and is consistent with evidence from Schizophyllum commune that (1-->6)-beta-glucan accumulates during maturation of the subapical region of the wall distal to the hyphal tip.