TABLE1Subunit composition and function of Ca2+ channel typesCa2+ currentPrimaryPrevious nameSpecificCa2+ channelFunctionstypelocalizationsof aysubunitsblockerLCay1.1DHPsSkeletalmuscleExcitation-contractioncouplingαisCalciumhomeostasisGene regulationLDHPsCay1.2CardiacmuscleExcitation-contractioncouplingα1cEndocrine cellsHormone secretionNeuronsGene regulationLDHPsCav1.3Endocrine cellsHormone secretionαIDNeuronsGene regulationLCav1.4RetinaTonicneurotransmitterreleaseαiFP/QCay2.1Nerve terminalsNeurotransmitter releaseo-Agatoxinα1ADendritesDendritic Ca2+ transientsNCav2.2Nerve terminalsO-CTx-GVIANeurotransmitterreleaseα1BDendritesDendritic Ca2+ transientsRNoneCav2.3Cell bodiesCa2+-dependent action potentialsα1EDendritesNerveNeurotransmitterreleaseTerminalsTNoneCay3.1Cardiac muscleRepetitive ringα1GSkeletal muscleNeuronsTCay3.2NoneCardiac muscleRepetitive ringα1HNeuronsTCay3.3NoneNeuronsRepetitive ringα1I
Subunit composition of theCa2+channel complex2+Caa2aS
Subunit composition of the Ca2+ channel complex
MolecularpropertiesofCa2+channelsfirst solubilized and purified from the transverse tubulemembranes ofskeletalmusclesubunits:α1,β,andα1andβsubunitsaresubstratesforcAMP-dependentproteinphosphorylationanadditionalα2osubunitcomigratingwiththe α1subunitglycosylation and hydrophobicity of thesefive subunits ledtoa model comprising a principal transmembrane α1subunit of 190kDainassociationwithadisulfide-linkedα28dimerof17okDa,anintracellularphosphorylatedbsubunitof55kDa,andatransmembranesubunitof33kDa
Molecular properties of Ca2+ channels first solubilized and purified from the transverse tubule membranes of skeletal muscle subunits: 1, , and 1 and subunits are substrates for cAMP-dependent protein phosphorylation an additional 2 subunit comigrating with the 1 subunit glycosylation and hydrophobicity of these five subunits led to a model comprising a principal transmembrane 1 subunit of 190 kDa in association with a disulfide-linked 2 dimer of 170 kDa, an intracellular phosphorylated b subunit of 55 kDa, and a transmembrane subunit of 33 kDa
Subunit structure of Cay channelsBα.2+H3NCO2'+H3Ndomain:outside0insideHH3CO2Lc02B+H3NcoYellow:voltage-sensingmoduleGreen:pore-formingmoduleLengthsoflines=Lengthsofthepolypeptidesegments
Subunit structure of Ca V channels Yellow: voltage-sensing module Green: pore-forming module Lengths of lines ≈ Lengths of the polypeptide segments
Membrane topology of α1 subunit of the VAcCIV川川S1S2S3S4S5SFHNHOOCDomainsSegmentsPoreregion
Membrane topology of 1 subunit of the VACC Domains Segments Pore region