Repeat

Major vault protein, N-terminal (IPR002499)

Short name: Vault_N

Description

Vaults are the largest ribonucleoprotein particles known, having a mass of approximately 13 MDa. They are multi-subunit structures that may act as scaffolds for proteins involved in signal transduction and may also play a role in nucleo-cytoplasmic transport. Vaults are present in most normal tissues, but are more highly expressed in epithelial cells with secretory and excretory functions, as well as in cells chronically exposed to xenobiotics, such as bronchial cells and cells lining the intestine [PMID: 16918321]. Overexpression of these proteins is linked with multidrug-resistance in cancer cells.

The mammalian vault structure is highly regular and consists of approximately 96 molecules of the 100 kDa major vault protein (MVP), 2 molecules of the 240 kDa minor vault protein TEP1, 8 molecules of the 193 kDa minor vault protein VPARP and at least 6 copies of a small untranslated RNA of 88-141 bases. The MVP molecules form the core of the complex, which is a barrel-like structure with an invaginated waist and two protruding caps. The complex can unfold into two symmetrical flower-like structures with 8 petals each supposedly consisting of 6 MVP molecules [PMID: 10196123].

The MVP protein is composed of two distinct domains [PMID: 16373071]. The N-terminal domain contains ~8 copies of the vault repeat (or MVP repeat) in tandem. The MVP repeat is composed of ~53 amino acids and forms a structural part of the vault wall. The C-terminal part of MVP may be involved in oligomerization and be located in the vault cap, while the MVP repeats in the N-terminal part can be packed like staves in a barrel to form the vault wall. The 3D structure of the repeat forms a fold that consists of a three stranded (B) antiparallel beta-sheet in a unique topology B2-B1-B3 and two loops. MVP repeats can be interaction-mediating modules, as MVP repeats 3 and 4 bind VPARP, which is one of the other vault proteins.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
PROSITE profiles