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The spliceosome: the most complex macromolecular machine in the cell?
Author(s) -
Nilsen Timothy W.
Publication year - 2003
Publication title -
bioessays
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.175
H-Index - 184
eISSN - 1521-1878
pISSN - 0265-9247
DOI - 10.1002/bies.10394
Subject(s) - spliceosome , snrnp , rna splicing , minor spliceosome , small nuclear ribonucleoprotein , intron , ribonucleoprotein , biology , computational biology , rna , genetics , group ii intron , small nuclear rna , splicing factor , microbiology and biotechnology , gene , non coding rna
The primary transcripts, pre‐mRNAs, of almost all protein‐coding genes in higher eukaryotes contain multiple non‐coding intervening sequences, introns, which must be precisely removed to yield translatable mRNAs. The process of intron excision, splicing, takes place in a massive ribonucleoprotein complex known as the spliceosome. Extensive studies, both genetic and biochemical, in a variety of systems have revealed that essential components of the spliceosome include five small RNAs–U1, U2, U4, U5 and U6, each of which functions as a RNA, protein complex called an snRNP ( s mall n uclear r ibonucleoprotein). In addition to snRNPs, splicing requires many non‐snRNP protein factors, the exact nature and number of which has been unclear. Technical advances, including new affinity purification methods and improved mass spectrometry techniques, coupled with the completion of many genome sequences, have now permitted a number of proteomic analyses of purified spliceosomes. These studies, recently reviewed by Jurica and Moore,1 reveal that the spliceosome is composed of as many as 300 distinct proteins and five RNAs, making it among the most complex macromolecular machines known. BioEssays 25:1147–1149, 2003. © 2003 Wiley Periodicals, Inc.