Prohibitin: Difference between revisions
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| summary_text = Prohibitins are evolutionarily conserved genes that are ubiquitously expressed. The human prohibitin gene, located on the BRCA1 chromosome region 17q21, was originally thought to be a negative regulator of cell proliferation and a tumor suppressor. This anti-proliferative activity was later attributed to the 3' UTR of the PHB gene, and not to the actual protein. Mutations in human PHB have been linked to sporadic breast cancer. Prohibitin is expressed as two transcripts with varying lengths of 3' untranslated region. The longer transcript is present at higher levels in proliferating tissues and cells, suggesting that this longer 3' untranslated region may function as a trans-acting regulatory RNA.<ref name="entrez">{{cite web | title = Entrez Gene: PHB prohibitin| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5245| accessdate = }}</ref> |
| summary_text = Prohibitins are evolutionarily conserved genes that are ubiquitously expressed. The human prohibitin gene, located on the BRCA1 chromosome region 17q21, was originally thought to be a negative regulator of cell proliferation and a tumor suppressor. This anti-proliferative activity was later attributed to the 3' UTR of the PHB gene, and not to the actual protein. Mutations in human PHB have been linked to sporadic breast cancer. Prohibitin is expressed as two transcripts with varying lengths of 3' untranslated region. The longer transcript is present at higher levels in proliferating tissues and cells, suggesting that this longer 3' untranslated region may function as a trans-acting regulatory RNA.阿<ref name="entrez">{{cite web | title = Entrez Gene: PHB prohibitin| url = http://www.ncbi.nlm.nih.gov/sites/entrez?Db=gene&Cmd=ShowDetailView&TermToSearch=5245| accessdate = }}</ref> |
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Revision as of 09:39, 4 September 2008
Template:PBB Prohibitin, also known as PHB, is a human gene.[1] Prohibitin genes have been described in animals, fungi, plants and unicellular eukaryotes. Prohibitins are divided in two classes, termed Type-I and Type-II prohibitins, based on their similarity to yeast PHB1 or PHB2, respectively. Each organism has at least one copy of each type of prohibitin gene.
Currently, it is thought that prohibitins form large ring-shaped protein complexes in the inner mitochondrial membrane that are essential for viability of multicellular organisms. The precise molecular function of the PHB complex is not clear, but a role as chaperone for respiration chain proteins or a as a general structuring scaffold required for optimal mitochondrial morphology and function are suspected. Recently, prohibitins have been demonstrated to be positive, rather than negative, regulators of cell proliferation in both plants and mice. In contrast, a large number of publications suggest that human PHB1 is a nuclear-localised repressor of the cell cycle, acting by direct binding and inhibition of the proliferation-stimulating transcription factor E2F. However, these experiments were mostly performed in transformed human cell lines and little evidence for nuclear targeting and E2F-binding of prohibitins has been found in actual humans or any other organism.
References
Further reading
- Van Aken O, Pecenkova T, van de Cotte B; et al. (2007). "Mitochondrial type-I prohibitins of Arabidopsis thaliana are required for supporting proficient meristem development". Plant J. 52 (5): 850–864. PMID 17883375.
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