TABLE 1.
Actin-activated MgATPase activity of HMM II-C before and after phosphorylation by MLCK
Actin-activated MgATPase activity was measured at 25 °C as described under “Experimental Procedures.” The values for Vmax and KATPase are the mean and S.D. from three to four experiments from three different protein preparations. II-C0, noninserted HMM II-C; II-C1, inserted HMM II-C with an 8-amino acid insert in loop 1; II-C2, inserted HMM II-C with a 41-amino acid insert in loop 2; II-C1C2, inserted HMM II-C with both C1 and C2 inserts; basal MgATPase is measured without actin.
|
HMMs |
Basal MgATPase, Vmax |
Actin-activated MgATPase |
|||
|---|---|---|---|---|---|
|
−MLCK |
+MLCK |
||||
| Vmax | KATPase | Vmax | KATPase | ||
| s−1 | s−1 | μm | s−1 | μm | |
| II-C0 | <0.006 | 0.03 ± 0.01 | 1.2 ± 0.7 | 0.16 ± 0.02 | 4.6 ± 1.6 |
| II-C1 | <0.007 | 0.04 ± 0.03 | 15.6 ± 13.3 | 0.21 ± 0.01 | 10.9 ± 4.6 |
| II-C2 | <0.04 | 0.34 ± 0.09 | 13.9 ± 6.9 | 0.27 ± 0.06 | 7.2 ± 5.5 |
| II-C1C2 | <0.02 | 0.36 ± 0.09 | 12.9 ± 5.4 | 0.26 ± 0.06 | 3.8 ± 1.7 |