Table 1.
Nucleotide and calcium binding to calreticulin and ATP hydrolysis by calreticulin
| Construct | Ligand | Technique | Kd, mM* | ∆H, kJ/mol* | Replicates | Km, mM* | Replicates |
| mCRT(WT) | ATP | FQ | 0.65 ± 0.09 | 30 | 0.47 ± 0.03 | 17 | |
| ADP | FQ | 1.02 ± 0.21 | 7 | ||||
| Ca2+ | ITC | 0.017 ± 0.001 | −89.50 ± 14.88 | 9 | |||
| mCRT(K7A) | ATP | FQ | 6.33 ± 0.70 | 8 | 2.68 ± 0.07 | 17 | |
| ADP | FQ | 7.57 ± 1.56 | 3 | ||||
| Ca2+ | ITC | 0.019 ± 0.004 | −37.10 ± 9.63 | 4 | |||
| mCRT(E8A) | ATP | FQ | 5.49 ± 1.45 | 5 | 2.51 ± 0.02 | 2 | |
| ADP | FQ | 8.52 ± 3.05 | 3 | ||||
| Ca2+ | ITC | ND† | ND† | 3 | |||
| mCRT(D12A) | ATP | FQ | 1.08 ± 0.17 | 4 | 2.20 ± 0.04 | 4 | |
| ADP | FQ | 1.22 ± 0.03 | 3 | ||||
| Ca2+ | ITC | 0.02 ± 0.002 | −18.64 ± 6.73 | 4 | |||
| mCRT(R19A) | ATP | FQ | 1.03 ± 0.16 | 3 | 2.01 ± 0.25 | 3 | |
| ADP | FQ | 1.53 ± 0.14 | 3 | ||||
| Ca2+ | ITC | 0.019 ± 0.005 | −14.09 ± 5.12 | 4 | |||
| mCRT(K63A) | ATP | FQ | 2.69 ± 0.58 | 2 | 2.04 ± 0.22 | 3 | |
| ADP | FQ | 1.69 ± 0.35 | 2 | ||||
| Ca2+ | ITC | 0.018 ± 0.004 | −28.35 ± 12.22 | 3 | |||
| mCRT(D311A) | ATP | FQ | 2.45 ± 0.5 | 4 | 1.33 ± 0.23 | 4 | |
| Ca2+ | ITC | ND† | ND† | 2 | |||
| mCRT(Q50A) | ATP | FQ | 1.18 ± 0.25 | 4 | 0.61 ± 0.08 | 3 | |
| mCRT(R145A) | ATP | FQ | 0.52 ± 0.04 | 3 | 0.44 ± 0.08 | 2 | |
| mCRT(K305A) | ATP | FQ | 0.52 ± 0.17 | 3 | 0.50 ± 0.08 | 2 | |
| mCRT(K334A) | ATP | FQ | 0.78 ± 0.25 | 5 | 0.52 ± 0.11 | 3 | |
| mCRT(Y92A) | ATP | FQ | 0.84 ± 0.09 | 2 | 0.45 ± 0.03 | 2 |
FQ, fluorescence quenching; ITC, isothermal titration calorimetry.
*
Values represent mean ± SEM.
†
No binding detected by the indicated method.