What is the function of Securin?
Preservation of sister chromatid cohesion until all chromosomes correctly bioriented relies on anaphase inhibitor securin, known as Pds1 in yeast and PTTG1 pituitary tumor transforming gene in mammals. Synthesized during S and G2, securin binds stoichiometric quantities of separase protease through insertion of reactive loop into separase active site, acting as pseudosubstrate and competitive inhibitor. Beyond inhibition, securin serves as chaperone promoting proper folding of separase, its accumulation in nucleus and stability. As long as securin remains associated, separase cannot cleave coh
Ref: Zou et al., Securin as Separase Inhibitor and Chaperone, Cell 1999; Uhlmann et al., Mechanism of Securin-Separase Regulation, Nature 2000.