E2s of Uncertain Function

UbclO is required for the biogenesis of the peroxisome, an oxidative organelle [75]. This E2 plays a role in peroxisomal protein import [76] and is recruited to the peroxisomal membrane through an interaction with a partner protein [77]. Membrane-localized UbclO also seems to be spatially proximal to PexlO, which has a RING-like domain [78]. Whether PexlO is a cognate E3 of UbclO remains to be determined, as does the mechanistic role of ubiquitin conjugation in peroxisome biogenesis. 

82] and other data implicate both E2s in this process in higher cells [82, 83]. However, mitotic cyclins are efficiently degraded in budding yeast ubc4/i and ubcllA strains, indicating that other E2 enzymes can support this essential function in S. cerevisiae [84]. 

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