SUMMARY PARAGRAPH for IRR1
IRR1 is an essential gene that encodes a subunit of the yeast cohesin complex, which is required for sister chromatid cohesion in mitosis and meiosis (2, 1, 5, 6, 7). The yeast cohesin complex includes Smc1p and Smc3p, two members of a conserved family of chromosomal ATPases, and Mcd1p (8, 9, 1, 6, 7). Cohesin associates with centromeres and other discrete sites along chromosome arms prior to metaphase; the association with centromeres requires the centromere protein Mif2p, the centromere binding complex CBF3, and Cse4p (10, 11, 12). Scc2p is not a stoichiometric cohesin subunit, but is required for the cohesin complex to associate with chromosomes (1).
Temperature-sensitive mutations in IRR1 cause premature dissociation of sister chromatids (1). Reduced expression of IRR1 alters colony morphology and causes defects in zygote formation and spore germination (4).
Cohesin complexes have been identified in other eukaryotes, including Xenopus, C. elegans, S. pombe, and human (6); proteins similar to Irr1p have been found in mouse, Drosophila, C. elegans, and S. pombe (1).
Last updated: 2000-05-05