YJR089W BIR1 SGDID:S000003849, Chr X from 587718-590582, Genome Release 64-1-1, Verified ORF, "Subunit of chromosomal passenger complex (CPC; Ipl1p-Sli15p-Bir1p-Nbl1p), which regulates chromosome segregation; required for chromosome bi-orientation and for spindle assembly checkpoint activation upon reduced sister kinetochore tension"