Vault (organelle)
| Vault Particle | |||||||||
|---|---|---|---|---|---|---|---|---|---|
Structure of the Vault complex from rat liver.
|
|||||||||
| Identifiers | |||||||||
| Symbol | Vault | ||||||||
| Pfam | PF01505 | ||||||||
| InterPro | IPR002499 | ||||||||
| PROSITE | PDOC51224 | ||||||||
|
|||||||||
| Available protein structures: | |
|---|---|
| Pfam | structures |
| PDB | RCSB PDB; PDBe; PDBj |
| PDBsum | structure summary |
The vault or vault cytoplasmic ribonucleoprotein is a eukaryotic organelle whose function is not fully understood. Discovered and isolated by cell biologist Nancy Kedersha and biochemist Leonard Rome in 1986, vaults are cytoplasmic organelles which when negative-stained and viewed under an electron microscope resemble the arches of a cathedral vaulted ceiling, with 39-fold (Or D39d) symmetry. They are present in many types of eukaryotic cells and appear to be highly conserved amongst eukaryotes.
Vaults are large ribonucleoprotein particles. About 3 times the size of a ribosome and weighing approximately 13 MDa, they are found in most eukaryotic cells and all higher eukaryotes. They measure 34 nm by 60 nm from a negative stain, 26 nm by 49 nm from cryo-electron microscopy, and 35 nm by 59 nm from STEM. The vaults consist primarily of proteins, making it difficult to stain with conventional techniques. The protein structure consists of an outer shell composed of 78 copies of the ~100 KDa major vault protein (MVP). Inside are two associated vault proteins, TEP1 and VPARP. TEP1, also known as the telomerase-associated protein 1, is 290 KDa and VPARP (also known as PARP4) is related to poly-(ADP-ribose) polymerase (PARP) and is 193 KDa. Vaults from higher eukaryotes also contain one or several small vault RNAs (vRNAs, also known as vtRNAs) of 86–141 bases within.
Despite not being fully elucidated, vaults have been associated with the nuclear pore complexes and their octagonal shape appears to support this. Vaults have been implicated in a broad range of cellular functions including nuclear-cytoplasmic transport, mRNA localization, drug resistance, cell signaling, nuclear pore assembly, and innate immunity. The three vault proteins (MVP, VPARP, and TEP1) have each been knocked out individually and in combination (VPARP and TEP1) in mice. All of the knockout mice are viable and no major phenotypic alterations have been observed. Dictyostelium encode three different MVPs, two of which have been knocked out singly and in combination. The only phenotype seen in the Dictyostelium double knockout was growth retardation under nutritional stress. If vaults are involved in an essential cellular functions, it seems likely that redundant systems exist that can ameliorate their loss.
...
Wikipedia