Calcium channel alpha2delta subunits: differential expression, function, and drug binding.
Voltage-activated calcium channels are transmembrane proteins that act as transducers of electrical signals into numerous intracellular activities. On the basis of their electrophysiological properties they are classified as high- and low-voltage-activated calcium channels. High-voltage-activated calcium channels are heterooligomeric proteins consisting of a pore-forming alpha1 subunit and auxiliary alpha2delta, beta, and--in some tissues--gamma subunits. Auxiliary subunits support the membrane trafficking of the alpha1 subunit and modulate the kinetic properties of the channel. In particular, the alpha2delta subunit has been shown to modify the biophysical and pharmacological properties of the alpha1 subunit. The alpha2delta subunit is posttranslationally cleaved to form disulfide-linked alpha2 and, delta proteins, both of which are heavily glycosylated. Recently it was shown that at least four genes encode for alpha2delta subunits which are expressed in a tissue-specific manner. Their biophysical properties were characterized in coexpression studies with high- and low-voltage-activated calcium channels. Mutations in the gene encoding alpha2delta-2 have been found to underlie the ducky phenotype. This mouse mutant is a model for absence epilepsy and is characterized by spike wave seizures and cerebellar ataxia. Alpha2delta subunits can also support pharmacological interactions with drugs that are used for the treatment of epilepsy and neuropathic pain.
Institut für Pharmakologie und Toxikologie, Technische Universität München, Bíedersteiner Str. 29, 80802 München, Germany. klugbauer@ipt.med.tu-muenchen.de
Norbert
N
Klugbauer
Else
E
Marais
Franz
F
Hofmann
D000085:Acetates / Q000494:pharmacology*; D000588:Amines; D000595:Amino Acid Sequence; D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D003509:Cyclohexanecarboxylic Acids; D000077206:Gabapentin; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D020836:Protein Structure, Quaternary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D013329:Structure-Activity Relationship; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D003509:Cyclohexanecarboxylic Acids; D011994:Recombinant Proteins; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin