A polyglutamine repeat or polyQ tract is a portion of a protein consisting of a sequence of several glutamine units. A repeat typically consists of about 10 to a few hundred such units.
Several genes, both in humans and in other species, contain a number of repetitions of the nucleotide triplet CAG or CAA. When the gene is translated into a protein, each of these triplets gives rise to a glutamine unit, resulting in a polyglutamine tract. Different alleles of such a gene often have different numbers of CAG/CAA triplets.
Searching with PatternmatchDB (15 or 20 Q)
|ATX8_HUMAN || Ataxin-8||yes|
|BMP2K_HUMAN|| BMP-2-inducible protein kinase|
|EAP1_HUMAN || Enhanced at puberty protein 1|
|EP400_HUMAN|| E1A-binding protein p400|
|FOXP2_HUMAN|| Forkhead box protein P2|
|FRPD3_HUMAN|| FERM and PDZ domain-containing protein 3|
|HD_HUMAN || Huntingtin||yes|
|MAML2_HUMAN|| Mastermind-like protein 2|
|MED12_HUMAN|| Mediator of RNA polymerase II transcription subunit 12|
|MN1_HUMAN || Probable tumor suppressor protein MN1|
|NCOA3_HUMAN|| Nuclear receptor coactivator 3|
|NCOA6_HUMAN|| Nuclear receptor coactivator 6|
|TBP_HUMAN || TATA-box-binding protein|
|THA11_HUMAN|| THAP domain-containing protein 11|
Trinucleotide repeat disorder
Why some Polyglutamine Repeat expand and others not?
Several inheritable neurodegenerative disorders, the polyglutamine diseases, caused by a CAG repeat expansion, occur if a mutation causes a polyglutamine tract in a specific gene to become too long.
Important examples of polyglutamine diseases are spinocerebellar ataxia and Huntington's disease
Further analysis indicated that there may be a toxic role of the RNA in polyQ-induced degeneration. We tested the role of the RNA by altering the CAG repeat sequence to an interrupted CAACAG repeat within the polyQ-encoding region; this dramatically mitigated toxicity. In addition, expression of an untranslated CAG repeat of pathogenic length conferred neuronal degeneration. These studies reveal a role for the RNA in polyQ toxicity, highlighting common components in RNA-based and polyQ-protein-based trinucleotide repeat expansion diseases.
RNA toxicity is a component of ataxin-3 degeneration in Drosophila 2008
Effect of Polyglutamine Repeats on Protein Function