Table 4. Comparative analysis of kinetic signatures of monomeric myosin-2 motor domain constructs.
Abbreviations used: NM2A: human nonmuscle myosin-2A, NM2B: human nonmuscle myosin-2B (PDB entry 4PD3); NM2C: human nonmuscle myosin-2C; SM: chicken smooth muscle myosin-2 (PDB entry 1BR2); CARD: human/chicken β-cardiac myosin-2 (PDB entry 4DB1); ST: rabbit/scallop striated muscle myosin-2 (PDB entry 1DFL).
| Myosin | kcat/Kapp | k+AD/K1k+2 | KAD/KD |
k-AD/ k-D |
KDA/KA | Duty ratio |
|---|---|---|---|---|---|---|
| Hs NM2C | 0.003 | 1.5 | 0.11 | 1 | 0.13 | ~0.3‡ |
| Hs R788K | 0.002 | n.d. | n.d. | 1 | 1 | ~0.3‡ |
| Hs R788E | 0.004 | 0.26 | 5 | 3 | 0.19 | ~1$ |
| Hs NM2A (Kovács et al., 2003) | 0.002 | 19.4 | 0.7 | 2.8 | 2 | 0.1 |
| Hs NM2B (Wang et al., 2003) | 0.002 | 10 | 0.2 | 0.7 | 0.4 | 0.37 |
| Gg SM (Marston and Taylor, 1980; Cremo and Geeves, 1998) | 0.07 | 4.4 | 4.2 | 12 | 6.9 | <0.05 |
| Hs/Gg CARD (Marston and Taylor, 1980; Deacon et al., 2012) | 0.07† | 1.6 | 42 | 103.3 | 23.9 | <0.02 |
| Oc/Ai ST (Ritchie et al., 1993; Kurzawa-Goertz et al., 1998; Wagner, 1981; Harris and Warshaw, 1993) | 1.6* | 1.6* | 49 | 250* | 30* | <0.04 |
*Rabbit striated muscle myosin-2.
†Chicken cardiac muscle myosin-2.
‡Calculated at 190 µM F-actin and saturating [ATP].