Investigating Antibody Access to Adsorbed Protein Nanocapsule Interiors Using the Quartz Crystal Microbalance and Surface Plasmon Resonance

Vaults are nanoscale, ribonucleoprotein capsules (41 nm × 41 nm × 72.5 nm [1]) comprised primarily of 96 self-assembled copies of one 96 kDa protein, termed MVP (major vault protein). When deposited on polylysine-coated mica and imaged using cryoelectron microscopy, vaults appear to “open” into flower-like structures with eight rectangular ‘petals’ [2]. Upon closer examination, each ‘flower’ consists of a central ring with hooks that attach each petal to the center. The flowers are usually seen in pairs, suggesting that each whole vault is composed of two flowers, folded so that the ends of their petals touch. It is likely that vaults in cells open and close in response to cellular signals, reversibly encapsulating and releasing their contents. However, whether vaults open into flower-like structures in vivo is unknown.