Fig. 6: Stick-slip model for CAG repeat aggregation in HD.
From: Stick-slip unfolding favors self-association of expanded HTT mRNA
A Short CAG tracts form composite hairpins that unfold and refold cooperatively with limited slippage of base pairs. B Expanded CAG repeats slip and rearrange non-cooperatively, producing a mixture of secondary structures that include unstable, slippery CAG hairpins (red) and stable, sticky CAG•CCG hairpins that unfold in small rips (red and gold). Single-stranded regions nucleate base pairing with another RNA, producing a network that can lead to aggregation (bottom). Although transitions between specific intermediate structures are not resolved in our experiments, the cartoons illustrate conformations consistent with the force-extension results.
