STAG domain proteins are subunits of cohesin complex - a protein complex required for sister chromatid cohesion in eukaryotes. The STAG domain is present in Schizosaccharomyces pombe mitotic cohesin Psc3, and the meiosis specific cohesin Rec11. Many organisms express a meiosis-specific STAG protein, for example, mice and humans have a meiosis specific variant called STAG3, although budding yeast does not have a meiosis specific version [1].

1: Cohesins are required for meiotic DNA breakage and recombination in Schizosaccharomyces pombe. Ellermeier C, Smith GR; Proc Natl Acad Sci U S A 2005;102:10952-10957. PMID:16043696