Vault (organelle)

From Wikipedia, the free encyclopedia

The vault or vault cytoplasmic ribonucleoprotein is a recently discovered eukaryotic organelle of which its function is not yet well known. Discovered and successfully isolated by biochemist Leonard Rome of the UCLA School of Medicine in the 1980s, vaults are cytoplasmic organelles which resemble a barrel, with eight-fold symmetry. They are present in many types of eukaryotic cells and appear to be highly conserved amongst eukaryotes[1].

Contents

[edit] Morphology

Vaults are large ribonucleoprotein particles. About 3 times the size of a ribosome and weighing approximately 13 MDa, they are found in many diverse eukaryotic cells. 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[2]. The vaults consist primarily of proteins, making it difficult to stain with conventional techniques. The protein structure consists of many major vault proteins (MVP) bound to one of the two minor vault proteins. Two large complexes of several MVP's and a minor vault protein close together to form the barrel-like vault organelle. They may contain small RNAs of 86–141 bases within[3].

[edit] Function

Despite not being fully elucidated, vaults have been associated with the nuclear pore complexes and their octagonal shape appears to support this[4]. It has been concluded that it is highly likely that vaults function in the transport of molecules, such as mRNA, from the nucleus to parts of the cytoplasm[5]. Additionally, vaults may also have a hand in protein synthesis[6].

[edit] Association with cancer

In the late 1990's, researchers found that vaults (especially the MVP) were over-expressed in cancer patients who were diagnosed with multidrug resistance, that is the resistance against many chemotherapy treatments[7]. Although this does not prove that increased number of vaults led to drug resistance, it did hint some sort of involvement. This has potential in discovering the mechanisms behind drug-resistance in tumor cells and improving anticancer drugs[8].

[edit] Extent of ubiquitous nature

Although vaults have been observed in many eukaryotic species, a few species do not appear to have the protein. These include[9]:

Albeit these exceptions, the high degree of similarity between organisms that do have vaults implies some sort of evolutionary importance[1].

[edit] See Also

[edit] External links

[edit] Literature

  1. ^ a b Kedersha, N. L., Miquel, M. C., Bittner, D. and Rome, L. H. (April 1990). "Vaults. II. Ribonucleoprotein structures are highly conserved among higher and lower eukaryotes." J. Cell Biol. 110, 895-901.
  2. ^ Kedersha, N. L., Heuser, J. E., Chugani, D. C. and Rome, L. H. (1991). "Vaults. III. Vault ribonucleoprotein particles open into flower-like structures with octagonal symmetry." J. Cell Biol. 112, 225-235.
  3. ^ A. van Zon, M. H. Mossink, R. J. Scheper, P. Sonneveld1 and E. A. C. Wiemer. "The vault complex" Cellular and Molecular Life Sciences (CMLS), Volume 60, Number 9, September, 2003; p 1828-1837
  4. ^ Unwin, P. N. T. and Milligan, R. A. (1982). "A large particle associated with the perimeter of the nuclear pore complex." J. Cell Biol. 93, 63-75.
  5. ^ Diane C. Chugani, Leonard H. Rome and Nancy L. Kedersha. "Evidence that vault ribonucleoprotein particles localize to the nuclear pore complex" Journal of Cell Science 106, 23-29 (1993)
  6. ^ Cindy L. Stanfield, William J. Germann "Principles of Human Physiology: Third Edition" Pearson Education Inc. 2008; p 41
  7. ^ Marieke H Mossink, Arend van Zon, Rik J Scheper, Pieter Sonneveld and Erik AC Wiemer. "Vaults: a ribonucleoprotein particle involved in drug resistance?" Oncogene (2003) 22, 7458–7467. doi:10.1038/sj.onc.1206947
  8. ^ Valerie A. Kickhoefer, Sanjay K. Vasu and Leonard H. Rome "Vaults are the answer, what is the question?" Trends in Cell Biology Volume 6, Issue 5, May 1996, Pages 174-178
  9. ^ Leonard Rome, Nancy Kedersha and Diane Chugani. "Unlocking vaults: organelles in search of a function." Trends in Cell Biology Volume 1, Issues 2-3, August-September 1991, Pages 47-50.
v • d • e
Organelles of the cell