Saccharomyces cerevisiae Csm1 is part of the monopolin complex. Csm1 forms a complex with Mde4 and promotes monoorientation during meiosis [1]. Csm1 also plays a mitotic role in DNA replication [1]. This family also contains the Schizosaccharomyces pombe homologue to Csm1, Pcs1. Pcs1 forms a complex with Mde4 and acts in the central kinetochore domain to clamp microtubule binding sites together [3]. The two complexes (Csm1/Lrs4 and Pcs1/Mde4) contribute to the prevention of merotelic attachment [3].

1: Saccharomyces cerevisiae CSM1 gene encoding a protein influencing chromosome segregation in meiosis I interacts with elements of the DNA replication complex. Wysocka M, Rytka J, Kurlandzka A; Exp Cell Res. 2004;294:592-602. PMID:15023545

2: Kinetochore recruitment of two nucleolar proteins is required for homolog segregation in meiosis I. Rabitsch KP, Petronczki M, Javerzat JP, Genier S, Chwalla B, Schleiffer A, Tanaka TU, Nasmyth K; Dev Cell. 2003;4:535-548. PMID:12689592

3: The kinetochore proteins Pcs1 and Mde4 and heterochromatin are required to prevent merotelic orientation. Gregan J, Riedel CG, Pidoux AL, Katou Y, Rumpf C, Schleiffer A, Kearsey SE, Shirahige K, Allshire RC, Nasmyth K; Curr Biol. 2007;17:1190-1200. PMID:17627824