دورية أكاديمية
Calcium ATPase of sarcoplasmic reticulum has four binding sites for calcium.
| العنوان: | Calcium ATPase of sarcoplasmic reticulum has four binding sites for calcium. |
|---|---|
| المؤلفون: | Jencks WP; Graduate Department of Biochemistry, Brandeis University, Waltham, Massachusetts 02254-9110., Yang T, Peisach D, Myung J |
| المصدر: | Biochemistry [Biochemistry] 1993 Jul 13; Vol. 32 (27), pp. 7030-4. |
| نوع المنشور: | Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S. |
| اللغة: | English |
| بيانات الدورية: | Publisher: American Chemical Society Country of Publication: United States NLM ID: 0370623 Publication Model: Print Cited Medium: Print ISSN: 0006-2960 (Print) Linking ISSN: 00062960 NLM ISO Abbreviation: Biochemistry Subsets: MEDLINE |
| أسماء مطبوعة: | Original Publication: Washington, American Chemical Society. |
| مواضيع طبية MeSH: | Calcium/*metabolism , Calcium-Transporting ATPases/*metabolism , Sarcoplasmic Reticulum/*enzymology, Animals ; Binding Sites ; Magnesium/metabolism ; Rabbits |
| مستخلص: | The calcium-transporting ATPase of sarcoplasmic reticulum is known to bind two Ca2+ ions from the cytoplasm to the free enzyme and two Ca2+ ions from the lumen to the phosphoenzyme. The concentration of phosphoenzyme formed at equilibrium from Pi and Mg2+ increases with increasing concentration of calcium in the lumen, which binds to the phosphoenzyme to form Ca2.E approximately P.Mg. However, at subsaturating concentrations of Mg2+ increasing the concentration of lumenal Ca2+ does not drive phosphoenzyme formation to completion. The maximal levels of phosphoenzyme that are formed at saturating concentrations of lumenal Ca2+ increase with increasing concentrations of Mg2+. This result requires that Ca2+ can bind to low-affinity lumenal sites on both the free enzyme and the phosphoenzyme, as well as to the high-affinity cytoplasmic calcium-binding sites. If there were no lumenal binding sites for Ca2+ on the free enzyme, high concentrations of lumenal Ca2+ would convert all of the enzyme to the same maximal concentration of Ca2.E approximately P.Mg at subsaturating concentrations of Mg2+ and Pi. We conclude that there are two low-affinity lumenal sites as well as two high-affinity cytoplasmic sites for Ca2+ on the free enzyme. Phosphorylation by ATP results in translocation of Ca2+ from the high-affinity to the low-affinity sites. |
| معلومات مُعتمدة: | GM20888 United States GM NIGMS NIH HHS |
| المشرفين على المادة: | EC 7.2.2.10 (Calcium-Transporting ATPases) I38ZP9992A (Magnesium) SY7Q814VUP (Calcium) |
| تواريخ الأحداث: | Date Created: 19930713 Date Completed: 19930820 Latest Revision: 20191210 |
| رمز التحديث: | 20221213 |
| DOI: | 10.1021/bi00078a031 |
| PMID: | 8334133 |
| قاعدة البيانات: | MEDLINE |
Find this issue from the American Chemical Society | تدمد: | 0006-2960 |
|---|---|
| DOI: | 10.1021/bi00078a031 |