Substrate specificity of the partially purified PM Ca2+-ATPase activity
| Assay Conditions | Nucleoside Triphosphatase Activity | |
|---|---|---|
| ATP | ITP | |
| nmol min−1 mg−1 protein | ||
| −Ca2+ | 0.27 | 0.25 |
| +Ca2+ | 0.70 (0.43) | 0.64 (0.39) |
| +Ca2+ + CaM | 3.26 (2.99) | 3.04 (2.79) |
Assays were performed as described in “Materials and Methods,” in the presence of 1 mm ATP or ITP; values in parentheses represent the Ca2+-dependent activities.