Single Particle Reconstruction of the Vault from TEP1 Knockout Mice and Refinement of the Computationally Selected Vault Barrel

Abstract The vault complex is a ubiquitous and predominantly cytoplasmic 13 MDa ribonucleoprotein assembly, composed of three proteins (TEP1, 240 kDa; VPARP, 193 kDa; and MVP, 100 kDa) and an untranslated RNA (vRNA) Although the basic cellular function of the vault is still unclear, recently it has been shown that induction of the major vault protein (MVP) has a direct negative influence on the nuclear uptake of the anti-cancer drug, doxorubicin. We have been applying cryo-EM single particle reconstruction methods to study the structure and molecular architecture of this cellular component. A published reconstruction of the intact rat vault at 31 Å resolution revealed that the complex is hollow and is structurally well suited to serve in macromolecular transport or sequestration. Higher resolution, 23 Å, was achieved for a reconstruction of the RNase-treated rat vault and difference imaging with the intact rat vault localized the vRNA to the ends of the vault caps.