Suppressed By

V29D
E150K[F3]
Y118F
H485R
E490G
Y494N
L495P
K496E
G507C
S619C
P650T[F7]
I656F[F6]

* = suppression is reciprocal

WHERE: Y494 lies near the end of the CamShaft (466-496). It 'rubs noses' with W501L and G691C.

WHAT: A tough nut to crack. A severe mutation biologically, its biochemistry (performed in collaboration with Taro Uyeda) is confusing at best. It has a high basal ATPase as a full-length myosin, but as an S1 (motor only) it doesn not. It inhibits movement by wild-type motors in mixtures. It's affinity to actin in the presence of ADP and high salt is less than that of wild-type. My current pet theory is that the 490-510 region changes secondary structure significantly during the cycle; Y494K would strengthen the alpha helical propensity of the region. The fact that Y494N is tolerated but Y494K is not is consistent with this explanation, as is suppression by L495P.

FRIENDS & RELATIONS: By proximity, mutual suppression by E150K[F3], Y118F, P650T and I656F, and some biochemical findings, Y494K is a twin of W501L[I5]. It is also very close to G691C, which is also suppressed by E150K[F3] (other suppressors not yet tested). It is one of the original cold-sensitive mutations (V192[D6], G240C, G240V, E467Q, E467K, Y494K, W501L[I5], E531Q[G12], P536R[G13], R562H[G10], R562L, E586K [F11], G624D, G680V, G691C, G740D). IT's location in the CamShaft places it 'alongside' E467Q,K, E476K, Q480H, H485R, M486I [G7] , K488E,E490G, L495P, K496E and G507C.

Image: Y494K is a primary mutant in the CamShaft Mirror