Functional genomics identifies Monopolin: A kinetochore protein required for segregation of homologs during meiosis I

The orderly reduction in chromosome number that occurs during meiosis depen ds on two aspects of chromosome behavior specific to the first meiotic divi sion. These are the retention of cohesion between sister centromeres and th eir attachment to microtubules that extend to the same pole (monopolar atta chment). By deleting genes that are upregulated during meiosis, we identifi ed in Saccharomyces cerevisiae a kinetochore associated protein, Mam1 (Mono polin), which is essential for monopolar attachment. We also show that the meiosis-specific cohesin, Rec8, is essential for maintaining cohesion betwe en sister centromeres but not for monopolar attachment. We conclude that mo nopolar attachment during meiosis I requires at least one meiosis-specific protein and is independent of the process that protects sister centromere c ohesion.