Channel Subunits
There are several different kinds of high-voltage-gated calcium channels (HVGCCs). They are structurally homologous among varying types; they are all similar, but not structurally identical. In the laboratory, it is possible to tell them apart by studying their physiological roles and/or inhibition by specific toxins. High-voltage-gated calcium channels include the neural N-type channel blocked by ω-conotoxinGVIA, the R-type channel (R stands for Resistant to the other blockers and toxins, except SNX-482) involved in poorly defined processes in the brain, the closely related P/Q-type channel blocked by ω-agatoxins, and the dihydropyridine-sensitive L-type channels responsible for excitation-contraction coupling of skeletal, smooth, and cardiac muscle and for hormone secretion in endocrine cells.
| Current Type | 1,4-dihydropyridine sensitivity (DHP) | ω-conotoxin sensitivity (ω-CTX) | ω-agatoxin sensitivity (ω-AGA) |
| L-type | blocks | resistant | resistant |
| N-type | resistant | blocks | resistant |
| P/Q-type | resistant | resistant | blocks |
| R-type | resistant | resistant | resistant |
Read more about this topic: Voltage-dependent Calcium Channel
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