Critical amino acid residues determine the binding affinity and the Ca2+ release efficacy of maurocalcine in skeletal muscle cells
| Autor: | Michel Ronjat, Paul D. Allen, Eric Estève, Csaba Szegedi, Xavier Altafaj, Sándor Sárközi, Jean-Marc Sabatier, Isabelle Marty, Imed Regaya, Isaac N. Pessah, Herré Rochat, Michel De Waard, Sophia Smida-Rezgui, Istvan Jona, Lili Chen |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
Molecular Sequence Data
Scorpion Venoms Peptide Biology Biochemistry Structure-Activity Relationship medicine Animals cardiovascular diseases Elméleti orvostudományok Amino Acid Sequence Muscle Skeletal Molecular Biology Cells Cultured RYR1 chemistry.chemical_classification Ryanodine receptor Ryanodine Endoplasmic reticulum Vesicle Skeletal muscle Ryanodine Receptor Calcium Release Channel Cell Biology Orvostudományok nervous system diseases Rats Sarcoplasmic Reticulum medicine.anatomical_structure chemistry cardiovascular system Maurocalcine Calcium Intracellular |
| Zdroj: | The Journal of biological chemistry. 278(39) |
| ISSN: | 0021-9258 |
| Popis: | Maurocalcine (MCa) is a 33 amino acid residue peptide toxin isolated from the scorpion Scorpio maurus palmatus. MCa and mutated analogues were chemically synthesized, and their interaction with the skeletal muscle ryanodine receptor (RyR1) was studied on purified RyR1, sarcoplasmic reticulum (SR) vesicles, and cultured myotubes. MCa strongly potentiates [3H]ryanodine binding on SR vesicles (7-fold at pCa 5) with an apparent EC50 of 12 nm. MCa decreases the sensitivity of [3H]ryanodine binding to inhibitory high Ca2+ concentrations and increases it to the stimulatory low Ca2+ concentrations. In the presence of MCa, purified RyR1 channels show long-lasting openings characterized by a conductance equivalent to 60% of the full conductance. This effect correlates with a global increase in Ca2+ efflux as demonstrated by MCa effects on Ca2+ release from SR vesicles. In addition, we show for the first time that external application of MCa to cultured myotubes produces a cytosolic Ca2+ increase due to Ca2+ release from 4-chloro-m-cresol-sensitive intracellular stores. Using various MCa mutants, we identified a critical role of Arg24 for MCa binding onto RyR1. All of the other MCa mutants are still able to modify [3H]ryanodine binding although with a decreased EC50 and a lower stimulation efficacy. All of the active mutants produce both the appearance of a subconductance state and Ca2+ release from SR vesicles. Overall, these data identify some amino acid residues of MCa that support the effect of this toxin on ryanodine binding, RyR1 biophysical properties, and Ca2+ release from SR. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|