Suppressed By

P128Q
L176F
I177M
G182C
*T189I[E7]
*V192[D6][D6]]
L216F
N235D
*G240C,N,V
E476Q
*N483S[G7]
*L638F

WHERE: G680 forms the 'elbow joint' in an alpha-helix running from 669-691. The joint is very close to the CamShaft (466-496), approaching most closely at N483 (site of G680V suppressor N483S)

WHAT: This mutation makes myosin stingier with ATP (lowers basal ATPase) and slows actin movement driven by wild-type filaments. At steady state, the G680V mutant is strongly bound to actin a much greater proportion of the time; the salt-sensitivity of this state does not match the ADP-bound or rigor forms of wild type or G680V (i.e. it is a different state). that Our hypothesis is that this mutation impedes Pi release by myosin. We presume this occurs by altering the disposition of the CamShaft, which in turn would render the 'gateway' (R238/E459) more difficult to open.

FRIENDS & RELATIONS: So far we have no other mutants that we know are similar to G680V in properties. It is one of the original cold-sensitive isolates, and amongst its suppressors are two others: V192[D6] and G240C,N. It is notably near to V681I, an *N483S[G7] suppressor.

Image: G680V can be found in the G680V mirror.