Involved in spore wall assembly (PubMed:23966878). May be involved in maintaining genome integrity (PubMed:18562670). During sporulation. Repressed during vegetative growth by HST1 and RFM1. N-glycosylated. Displays elevated rates of loss of heterozygosity (LOH) (PubMed:18562670). A combined deletion of the LOH1/OSW4 and IRC18/OSW6 has reduced dityrosine incorporation in the outer spore wall (PubMed:23966878). Belongs to the OSW4/6 family.