| Autor: |
W. Barry Van Winkle, A. Chu, Mark L. Entman, Roger J. Bick, C. A. Tate |
| Rok vydání: |
1986 |
| Předmět: |
|
| Zdroj: |
Journal of Molecular and Cellular Cardiology. 18:781-791 |
| ISSN: |
0022-2828 |
| DOI: |
10.1016/s0022-2828(86)80953-1 |
| Popis: |
Our previous data suggested that, in cardiac muscle sarcoplasmic reticulum fragments, GTP hydrolysis occurs by an alternative enzyme cycle of the Ca2+ ATPase which is insensitive to (Ca2+) and does not involve an acyl phosphate intermediate. Despite this, GTP induces the incorporation of calcium into a membrane pool that is not translocated to the vesicular lumen. The present study suggests that this GTP-induced intermediate calcium pool is identical to a modulable component of the calcium translocation process in that: it has an identical pH sensitivity; the initial incorporation of calcium in response to GTP eliminates the initial rapid burst and lag component of the typical ATP-induced calcium uptake curve when ATP is added during GTP-induced calcium accumulation. Instead, the addition of ATP during GTP-induced calcium accumulation results in the prompt onset of the linear phase of calcium translocation; GTP-induced calcium accumulation directly affects the pH sensitivity of subsequent ATP-induced calcium accumulation. We suggest that the intermediate calcium pool is in series with calcium translocation and is the site of the pH sensitivity observed in calcium flux. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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