Immunofluorescent Identification of α1 Isoform Subunits of Voltage-Gated Ca2+-Channels of CaV1, CaV2, and CaV3 Families in Areas of Cholinergic Synapses of Somatic Muscles in Earthworm Lumbricus terrestris

Abstract

The α1 subunits of the voltage-gated Ca2+-channels α1S, α1C, α1D, and α1F in channels of the CaV1.1–1.4 type; α1A in a channel of CaV2.1 type; α1E in a channel of CaV2.3 type; and α1G, α1H, and α1I in a channel of CaV3.1–3.3 type, as well as the synaptic vesicle exo-endocytotic protein synaptophysin, were identified using fluorescence and confocal microscopy in the somatic muscle of the earthworm Lumbricus terrestris. The presynaptic membrane of cholinergic synapses contains voltage-gated Ca2+-channels of CaV1.1 and CaV1.2 (including α1S and α1C subunits), CaV2.1 (with α1A subunit), CaV2.3 (with α1E subunit), and CaV3.2 and CaV3.3 (with subunits α1H, α1I) types, while CaV1.3 and CaV1.4 Ca2+-channels with subunits α1D and α1F and CaV3.1 channels with subunit α1G are predominantly parts of the muscle membranes.