Interactions between N and C termini of α1Csubunit regulate inactivation of CaV1.2 L-type Ca2+channel
| Autor: | Adva Benmocha Guggenheimer, Vladimir Tsemakhovich, Joel A. Hirsch, Nathan Dascal, Lior Almagor, Debi Ranjan Tripathy |
|---|---|
| Rok vydání: | 2015 |
| Předmět: |
0301 basic medicine
Calcium Channels L-Type Calmodulin Xenopus Protein subunit Molecular Sequence Data Biophysics Bioinformatics Models Biological Biochemistry Cav1.2 Structure-Activity Relationship 03 medical and health sciences Protein Interaction Mapping Animals Amino Acid Sequence chemistry.chemical_classification biology Calcium channel C-terminus Cell Membrane Transmembrane protein Amino acid Protein Subunits Cytosol 030104 developmental biology chemistry Mutagenesis Mutation biology.protein Rabbits Ion Channel Gating Protein Binding Research Paper |
| Zdroj: | Channels. 10:55-68 |
| ISSN: | 1933-6969 1933-6950 |
| Popis: | The modulation and regulation of voltage-gated Ca(2+) channels is affected by the pore-forming segments, the cytosolic parts of the channel, and interacting intracellular proteins. In this study we demonstrate a direct physical interaction between the N terminus (NT) and C terminus (CT) of the main subunit of the L-type Ca(2+) channel CaV1.2, α1C, and explore the importance of this interaction for the regulation of the channel. We used biochemistry to measure the strength of the interaction and to map the location of the interaction sites, and electrophysiology to investigate the functional impact of the interaction. We show that the full-length NT (amino acids 1-154) and the proximal (close to the plasma membrane) part of the CT, pCT (amino acids 1508-1669) interact with sub-micromolar to low-micromolar affinity. Calmodulin (CaM) is not essential for the binding. The results further suggest that the NT-CT interaction regulates the channel's inactivation, and that Ca(2+), presumably through binding to calmodulin (CaM), reduces the strength of NT-CT interaction. We propose a molecular mechanism in which NT and CT of the channel serve as levers whose movements regulate inactivation by promoting changes in the transmembrane core of the channel via S1 (NT) or S6 (pCT) segments of domains I and IV, accordingly, and not as a kind of pore blocker. We hypothesize that Ca(2+)-CaM-induced changes in NT-CT interaction may, in part, underlie the acceleration of CaV1.2 inactivation induced by Ca(2+) entry into the cell. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|