Probably functions in cell division and growth processes. Interacts with certain SNAREs as part of specialized membrane fusion events where vesicles from the same organelle fuse (homotypic fusion) (By similarity). Homohexamer (PubMed:15498773, PubMed:17190830). Interacts with SERK1, GRF6, KAPP and SYP31, but not with KNOLLE. Component of the SERK1 signaling complex, composed of KAPP, CDC48A, GRF6 or GRF7, SERK1, SERK2, SERK3/BAK1 and BRI1 (PubMed:12427991, PubMed:15592873, PubMed:16621602, PubMed:17693538, PubMed:23747397). Interacts with PUX1, PUX2, PUX3, PUX4, PUX5, PUX7 and PUX11 via its N-terminus (PubMed:15498773, Ref.7, PubMed:17190830). Primarily localized to the nucleus and, during cytokinesis, to the phragmoplast, a site where membrane vesicles are targeted in the deposition of new cell wall materials. Highly expressed in the proliferating cells of the vegetative shoot, root, floral inflorescence and flowers, and in rapidly growing cells. Phosphorylated on at least one threonine residue and on Ser-41 by SERK1. Belongs to the AAA ATPase family.