摘要：

▪ Abstract Voltage-gated Ca2+ channels mediate Ca2+ entry into cells in response to membrane depolarization. Electrophysiological studies reveal different Ca2+ currents designated L-, N-, P-, Q-, R-, and T-type. The high-voltage-activated Ca2+ channels that have been characterized biochemically are complexes of a pore-forming α1 subunit of ∼190–250 kDa; a transmembrane, disulfide-linked complex of α2 and δ subunits; an intracellular β subunit; and in some cases a transmembrane γ subunit. Ten α1 subunits, four α2δ complexes, four β subunits, and two γ subunits are known. The Cav1 family of α1 subunits conduct L-type Ca2+ currents, which initiate muscle contraction, endocrine secretion, and gene transcription, and are regulated primarily by second messenger-activated protein phosphorylation pathways. The Cav2 family of α1 subunits conduct N-type, P/Q-type, and R-type Ca2+ currents, which initiate rapid synaptic transmission and are regulated primarily by direct interaction with G proteins and SNARE proteins...

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