Identification and Characterization of Novel Human Cav2.2 (α1B) Calcium Channel Variants Lacking the Synaptic Protein Interaction Site
| Autor: | Hironobu Yamasaki, Atsushi Suzuki, Masamichi Satoh, Conan B. Cooper, Akinori Akaike, Naoto Nishioka, Shuji Kaneko, Gerald W. Zamponi, Scott E. Jarvis |
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| Rok vydání: | 2002 |
| Předmět: |
Patch-Clamp Techniques
Transcription Genetic Molecular Sequence Data Neurotransmission Biology N-type calcium channel Kidney Transfection Polymerase Chain Reaction Syntaxin binding Cell Line Calcium Channels N-Type GTP-Binding Proteins Humans Syntaxin RNA Messenger Cloning Molecular ARTICLE Gene Library Sequence Deletion Genetics Binding Sites Sequence Homology Amino Acid Qa-SNARE Proteins cDNA library General Neuroscience Calcium channel Brain Membrane Proteins Exons Introns Protein Structure Tertiary R-type calcium channel Alternative Splicing Barium Organ Specificity Biophysics Linker |
| Zdroj: | The Journal of Neuroscience. 22:82-92 |
| ISSN: | 1529-2401 0270-6474 |
| DOI: | 10.1523/jneurosci.22-01-00082.2002 |
| Popis: | The physical interaction between the presynaptic vesicle release complex and the large cytoplasmic region linking domains II and III of N-type (Cav2.2) calcium channel α1Bsubunits is considered to be of fundamental importance for efficient neurotransmission. By PCR analysis of human brain cDNA libraries and IMR32 cell mRNA, we have isolated novel N-type channel variants, termed Cav2.2-Δ1 and Δ2, which lack large parts of the domain II–III linker region, including the synaptic protein interaction site. They appear to be widely expressed across the human CNS as indicated by RNase protection assays. When expressed in tsA-201 cells, both novel variants formed barium-permeable channels with voltage dependences and kinetics for activation that were similar to those observed with the full-length channel. All three channel types exhibited the hallmarks of prepulse facilitation, which interestingly occurred independently of G-protein βγ subunits. By contrast, the voltage dependence of steady-state inactivation seen with both Δ1 and Δ2 channels was shifted toward more depolarized potentials, and recovery from inactivation of Δ1 and Δ2 channels occurred more rapidly than that of the full-length channel. Moreover, the Δ1 channel was dramatically less sensitive to both ω-conotoxin MVIIA and GVIA than either the Δ2 variant or the full-length construct. Finally, the domain II–III linker region of neither variant was able to effectively bind syntaxinin vitro. These results suggest that the structure of the II–III linker region is an important determinant of N-type channel function and pharmacology. The lack of syntaxin binding hints at a unique physiological function of these channels. |
| Databáze: | OpenAIRE |
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