The AAA+ ATPase p97 is a molecular machine with diverse cellular functions. We have demonstrated that the adaptor protein ASPL unexpectedly converts p97 hexamers into functional p97:ASPL hetero-tetramers. Now we plan to identify proteins that specifically associate with p97:ASPL heterotetramers by quantitative MS-based proteomics methods and to investigate the molecular mechanisms by which p97:ASPL complexes maintain the Golgi structure and localization in mammalian cells. To complement the functional studies we plan to examine the formation of p97:ASPL heterotetramers and the binding of ligand proteins to these complexes using biochemical and structural methods.