Linked Life Data

7697123

Source:http://linkedlifedata.com/resource/pubmed/id/7697123

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4-6
pubmed:dateCreated
1995-4-28
pubmed:abstractText
Eukaryotic proteasomes are unusually large protein complexes with characteristic sets of subunits and have been classified into two isoforms with apparent sedimentation coefficients of 20S and 26S, respectively. The 20S proteasome (previously named the multicatalytic proteinase complex) is a cylindrical particle with a molecular weight (MW) of approximately 750 kD. It is a dimeric assembly of two symmetrical discs, each consisting of 7 alpha-type subunits and 7 beta-type subunits, having the molecular organization alpha n[1-7)beta n[1-7)beta n[1-7)alpha n[1-7), where 'n' indicates the number of heterogeneous 7 subunits with MWs of 21-32 kD. The alpha-type and beta-type subunits constitute a unique multi-gene family encoding previously unidentified, but homologous, polypeptides that have been conserved during evolution. Interestingly, some beta-type subunits with catalytic functions appear to be replaced by very homologous, but distinct, gene products that might be generated by gene duplication in response to extracellular signals, such as gamma-interferon, suggesting that the 20S proteasome exists in cells as a heterogeneous population with functional diversity. The 26S proteasome is a eukaryotic ATP-dependent protease, selectively degrading various cellular proteins with specific degradation signals such as a multi-ubiquitin chain. It is a cylindrical caterpillar-shaped complex with a MW of about 2,000 kD. The 26S proteasome is a symmetrical assembly of a central 20S proteasome and a large terminal polypeptide complex with an apparent sedimentation coefficient of 22S. The terminal 22S subset consists of multiple components with MWs of 30-110 kD, which possibly have regulatory functions, and contains multiple ATPases, a de-ubiquitinating enzyme and the recognition molecule(s) for the target proteins. Thus the 26S proteasome is a multi-molecular assembly, consisting of the 20S proteasome and the 22S regulatory subunit complex.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:issn
1019-6773
pubmed:author
pubmed:issnType
Print
pubmed:volume
47
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
241-51
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1993
pubmed:articleTitle
Molecular structure of 20S and 26S proteasomes.
pubmed:affiliation
Institute for Enzyme Research, University of Tokushima, Japan.
pubmed:publicationType
Journal Article, Review, Research Support, Non-U.S. Gov't