Conformational changes of the in situ red cell membrane calcium pump affect its proteolysis
| Autor: | Ágnes Enyedi, Balázs Sarkadi, G. Gárdos |
|---|---|
| Rok vydání: | 1987 |
| Předmět: |
Protein Conformation
Proteolysis Calcium pump Biophysics chemistry.chemical_element Calcium-Transporting ATPases Pronase Calcium Biochemistry chemistry.chemical_compound medicine Humans Trypsin Vanadate Egtazic Acid medicine.diagnostic_test Chemistry Erythrocyte Membrane Vanadium Cell Biology Membrane transport Kinetics EGTA Vanadates medicine.drug |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 899:129-133 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/0005-2736(87)90247-1 |
| Popis: | In inside-out red cell membrane vesicles trypsin digestion reduces the molecular mass of the 32P-labeled acyl-phosphate intermediate of the calcium pump from the original 140 kDa to about 80 kDa with a simultaneous activation of the calcium uptake. This process is slightly stimulated by the presence of calcium, as compared to EGTA, or EGTA + vanadate, but the proteolytic pattern is similar under all these conditions. However, trypsin degradation of the 80 kDa polypeptide, resulting in the loss of calcium transport activity and 32P-phosphoenzyme formation, is rapid in the presence of calcium, inhibited by EGTA and almost fully blocked by EGTA + vanadate. In the presence of these latter ligands, probably locking the calcium pump in an E2 conformation, the 80 kDa protein becomes insensitive even to excessive digestion by the non-specific protease, pronase. The data indicate major changes in the molecular arrangement of the calcium pump protein when transformed from a calcium-liganded (E1) to an E2 conformation. |
| Databáze: | OpenAIRE |
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