Maintaining sister chromatid cohesion is essential for maintaining genomic integrity. Cohesin is necessary for regulating cohesion throughout the cell cycle as well as facilitating DNA damage repair and transcriptional regulation. Cohesion is established and maintained between the newly replicated sister chromatids throughout the cell cycle and into mitosis, where majority of cohesin is removed. In eukaryotes, cohesin is removed in two steps, during prophase, when arm cohesin is removed, and during anaphase, when cohesin is cleaved by separase at the centromeres. The main goal of this thesis is to establish the mechanism of arm cohesin removal during prophase through the Cdc48 segregase pathway. The data supports that two of the cohesin subunit's, Psm1 and Psm3, are ubiquitinated and that this acts as an event for Cdc48 complexes to bind to the targeted ubiquitinated arm cohesin to be removed from the chromosomes to allow for the sister chromatids to segregate.