SNCA is monoubiquitinated and under some circumstances released to accumulate in the cell. Alternatively Ub-SNCA may undergo further rounds of ubiquitination producing diubiquitinated or polyubiquitinated forms. The precise mechanism of release and subsequent further ubiquitination is unclear (Sadowski et al. 2011); the E3 ligase may remain bound to SNCA while the E2 ligase dissociates to be replaced by a Ubiquitin-associated replacement, or the E2/E3 complex may dissociate completely allowing a different E3 to bind the SNCA substrate.
