Worms have fewer filaments in their muscles when there's too much UNC-45 chaperone (top).

Chaperones protect proteins during their vulnerable folding stages. But too much chaperoning is counterproductive, as it keeps proteins in this vulnerable stage for too long, suggest Landsverk et al. (page 205).

The UNC-45 chaperone protects immature myosin from degradation while it folds into a form compatible with assembly into myofilaments. Without UNC-45, worms have fewer myofilaments in their muscle cells and are, as a result, severely paralyzed. The team now shows, however, that too much UNC-45 also results in myosin degradation, reduced myofilament numbers, and decreased mobility.

Myosin degradation caused by the loss of UNC-45 occurs via ubiquitination-mediated targeting to the proteasome. This same pathway was also the fate of myosin in the presence of too much UNC-45. Inhibiting the proteasome restored myosin levels and worm mobility.

The authors propose...

The Rockefeller University Press
2007
The Rockefeller University Press
2007
You do not currently have access to this content.