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