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)
| Uniprot | full name | expander |
| ANDR_HUMAN | Androgen Receptor | yes |
| ARI1B_HUMAN |
| ATX2_HUMAN | Ataxin-2 | yes |
| ATX8_HUMAN | Ataxin-8 | yes |
| BMP2K_HUMAN | BMP-2-inducible protein kinase |
| EAP1_HUMAN | Enhanced at puberty protein 1 |
| CBP_HUMAN |
| CELF3_HUMAN |
| DEN4B_HUMAN |
| EAP1_HUMAN |
| EP400_HUMAN | E1A-binding protein p400 |
| F157C_HUMAN |
| F171B_HUMAN |
| FOXP2_HUMAN | Forkhead box protein P2 |
| FRPD3_HUMAN | FERM and PDZ domain-containing protein 3 |
| HD_HUMAN | Huntingtin | yes |
| K2018_HUMAN |
| KCNN3_HUMAN |
| MAGI1_HUMAN |
| MAML2_HUMAN | Mastermind-like protein 2 |
| MAML3_HUMAN |
| MED15_HUMAN |
| 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 |
| NFAT5_HUMAN |
| NUMBL_HUMAN |
| PHC1_HUMAN |
| PHLA1_HUMAN |
| RUNX2_HUMAN |
| SATB1_HUMAN |
| SMCA2_HUMAN |
| TBP_HUMAN | TATA-box-binding protein |
| THA11_HUMAN | THAP domain-containing protein 11 |
| ZFHX3_HUMAN |
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
Pathogenesis
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
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