Huntington 1 (IMAGE) Rice University Caption Huntintin protein fragments with 40 repeats of polyglutamine progress from top to bottom toward aggregation in a simulation by scientists at Rice University. The polyglutamine fragments in orange fold into stiff hairpin shapes when they reach 30 polyglutamine repeats. The Rice researchers found the N-terminal region (green) encourages aggregation but is held in check by the proline C-terminus (blue) until polyglutamines reach a critical 36 repeats. Aggregation is suspected of causing Huntington's disease. Credit Mingchen Chen/Rice University Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.