separcase

Separase is a crucial enzyme in cell biology, belonging to the family of cysteine proteases. Its primary function is to catalyze the cleavage of the cohesin complex, a protein ring that holds sister chromatids together after DNA replication. This precise cleavage event is essential for the proper segregation of chromosomes during cell division, specifically during the transition from metaphase to anaphase. Without functional separase, sister chromatids would remain tethered, leading to aneuploidy, a condition where cells have an abnormal number of chromosomes.

The activity of separase is tightly regulated. It is kept in an inactive state by binding to an inhibitory protein called securin. During the cell cycle, securin is targeted for degradation by the anaphase-promoting complex/cyclosome (APC/C), a ubiquitin ligase. Once securin is removed, separase is free to act, initiating the breakdown of cohesin and allowing sister chromatids to separate and move to opposite poles of the cell. This regulated activation ensures that chromosome segregation occurs only at the appropriate time.

Dysregulation of separase activity has been implicated in various diseases, most notably cancer. Errors in chromosome segregation due to faulty separase function can contribute to tumor formation and progression. Consequently, separase has become a target for developing anti-cancer therapies, with inhibitors designed to disrupt its activity and potentially halt the proliferation of cancer cells.