 Clb5 processivity is dependent on the T5 and T33 sites, while Cln2 processivity is dependent on T5.Reintroduction of various residues led to the discovery of the T33 residue serving as a docking site for the T45/T48 phosphodegron pair, which is able to promote Sic1 degradation to a certain extent in the absence of other phosphodegron pairs.The following is a proposed mechanism by Koivomagi et al.