Fig. 8

Collaboration of UFD-2 and UNC-45 with quality-control muscle myosin. UNC-45 is a myosin chaperone that teams up with Hsp70/Hsp90 to promote the folding and assembly of muscle myosin (left). Our data show that the UFD-2 ubiquitin ligase is another partner protein of UNC-45, re-directing the chaperone toward a ubiquitination pathway. Upon binding to its TPR domain (red), the UFD-2 E3 ligase gets properly positioned to poly-ubiquitinate a presented protein, either the UCS domain (gray) of UNC-45 itself or a UCS-bound myosin (green). Importantly, UFD-2 has a clear preference for marking unfolded proteins, as indicated