Author/Editor		Albà, M. Mar; Santibáñez-Koref, Mauro F.; Hancock, John M.
Title		The comparative genomics of polyglutamine repeats: extreme differences in the codon organization of repeat-encoding regions between mammals and Drosophila
Type		članek
Vol. and No.		Letnik 52, št. 3
Publication year		2001
Volume		str. 249-259
ISSN		0022-2844 - Journal of molecular evolution
Language		eng
Abstract		Polyglutamine repeats within proteins are common in eukaryotes and are associated with neurological diseases in humans. Many are encoded by tandem repeats of the codon CAG that are likely to mutate primarily by replication slippage. However, a recent study in the yeast Saccharomyces cerevisiae has indicated that many others are encoded by mixtures of CAG and CAA which are less likely to undergo slippage. Here we attempt to estimate the proportions of polyglutamine repeats encoded by slippage-prone structures in species currently the subject of genome sequencing projects. We find a general excess over random expectation of polyglutamine repeats encoded by tandem repeats of codons. We nevertheless find many repeats encoded by nontandem codon structures. Mammals and Drosophila display extreme opposite patterns. Drosophila contains many proteins with polyglutamine tracts but these are generally encoded by interrupted structures. These structures may have been selected to be resistant to slippage. In contrast, mammals (humans and mice) have a high proportion of proteins in which repeats are encoded by tandem codon structures. In humans, these include most of the triplet expansion disease genes.
Keywords		analiza genomov glutaminske ponovitve evolucija genoma genome analysis glutamine repeats genome evolution