p37 Is a p97 Adaptor Required for Golgi and ER Biogenesis in Interphase and at the End of Mitosis

We previously reported that p97/p47-assisted membrane fusion is important for the reassembly of organelles at the end of mitosis, but not for their maintenance during interphase. We have now identified a p97 adaptor protein, p37, which forms a complex with p97 in the cytosol and localizes to the Golgi and ER. siRNA experiments revealed that p37 is required for Golgi and ER biogenesis. Injection of anti-p37 antibodies into cells at different cell cycle stages showed that p37 plays an important role in both Golgi and ER maintenance during interphase as well as in their reassembly at the end of mitosis. In an in vitro Golgi reassembly assay, the p97/p37 complex has membrane fusion activity. In contrast to the p97/p47 pathway, this pathway requires p115-GM130 tethering and SNARE GS15, but not syntaxin5. Interestingly, although VCIP135 is also required, its deubiquitinating activity is unnecessary for p97/p37-mediated activities.