Table 4. Contributions to ΔΔG and ΔpKa from important charged amino acids in GCaMP2 and GCaMP6m.
| GCaMP2 amino acid | GCaMP6m amino acid | Position with respect to pocket | Contribution to ΔΔG (kJ/mol) | Contribution to ΔpKa | |||
|---|---|---|---|---|---|---|---|
| Ca2+-free | Ca2+-saturated | GCaMP2 | GCaMP6m | GCaMP2 | GCaMP6m | ||
| E61 | E60 | in | in | 11.0 | 11.0 | 1.92 | 1.92 |
| E357 | E356 | out | in | -6.8 | -6.8 | -1.19 | -1.19 |
| E387 | E386 | out | in | -16.3 | -16.3 | -2.86 | -2.86 |
| E386 | E385 | in | out | 4.8 | 4.8 | 0.84 | 0.84 |
| D381 | Y380 | in | in | -4.6 | — | -0.81 | — |
| D383 | D382 | out | in | -6.1 | -6.1 | -1.07 | -1.07 |
| D305 | D304 | in | out | 6.8 | 6.8 | 1.19 | 1.19 |
| R377 | R376 | out | in | 5.4 | 5.4 | 0.95 | 0.95 |
| K378 | K377 | out | in | 6.1 | 6.1 | 1.07 | 1.07 |
| K380 | S379 | out | in | 9.0 | — | 1.58 | — |
| T382 | R381 | in | in | — | 1.4 | — | 0.246 |
| Total ΔΔG (kJ/mol) or ΔpKa (calculated): | 9.3 | 6.3 | 1.6 | 1.1 | |||
| Total ΔΔG (kJ/mol) or ΔpKa (experimental): | — | — | 1.7* | 0.91 | |||
*[11]