p97/valosin-containing protein (VCP) is highly modulated by phosphorylation and acetylation

p97/valosin-containing protein (VCP) is a member of the AAA family proteins, which plays various important roles in cells by using its ATPase activity. But mechanism of regulating its ATPase activity is mostly unknown. We report here that VCP is highly modified throughout the protein via acetylation and phosphorylation. In addition to six previously identified phosphorylation sites, we identified at least 14 serines, 14 threonines, 6 tyrosines and 22 lysines as potential modification sites. Interestingly, these sites included Lys²⁵¹ and Lys⁵²⁴, which are very critical for the ATP binding in Walker A motif of D1 and D2 domains, respectively. It is notable that 16 sites are in the N-terminal region and 16 sites are clustered in D2α domain (from Pro⁶⁴⁶ to Gly⁷⁶⁵). Indeed, amino acid substitution of Lys⁶⁹⁶ and Thr⁷⁶¹ profoundly affect VCP ATPase activities. From these results, we propose that D2α domain acts as a V CP A TPase R egulatory domain or "VAR domain". VCP modifications including those in this VAR domain may endorse adaptive and multiple functions to VCP in different cell conditions such as in the cell cycle and with abnormal protein accumulation.