The novel anticonvulsant drug, gabapentin (Neurontin), binds to the alpha2delta subunit of a calcium channel.
Gabapentin (1-(aminomethyl)cyclohexane acetic acid; Neurontin) is a novel anticonvulsant drug, with a mechanism of action apparently dissimilar to that of other antiepileptic agents. We report here the isolation and characterization of a [3H]gabapentin-binding protein from pig cerebral cortex membranes. The detergent-solubilized binding protein was purified 1022-fold, in a six-step column-chromatographic procedure, with a yield of 3.9%. The purified protein had an apparent subunit Mr of 130,000, and was heavily glycosylated. The partial N-terminal amino acid sequence of the Mr 130,000 polypeptide, EPFPSAVTIK, was identical to that reported for the alpha2delta subunit of the L-type Ca2+ channel from rabbit skeletal muscle (Hamilton, S. L., Hawkes, M. J., Brush, K., Cook, R., Chang, R. J., and Smilowitz, H. M. (1989) Biochemistry 28, 7820-7828). High levels of [3H]gabapentin binding sites were found in membranes prepared from rat brain, heart and skeletal muscle. Binding of [3H]gabapentin to COS-7 cells transfected with alpha2delta cDNA was elevated >10-fold over controls, consistent with the expression of alpha2 delta protein, as measured by Western blotting. Finally, purified L-type Ca2+ channel complexes were fractionated, under dissociating conditions, on an ion-exchange column; [3H]gabapentin binding activity closely followed the elution of the alpha2 delta subunit. [3H]Gabapentin is the first pharmacological agent described that interacts with an alpha2delta subunit of a voltage-dependent Ca2+ channel.
Gee
N S
NS
Parke-Davis Neuroscience Research Centre, Cambridge University Forvie Site, Robinson Way, Cambridge CB2 2QB, United Kingdom.
Brown
J P
JP
Dissanayake
V U
VU
Offord
J
J
Thurlow
R
R
Woodruff
G N
GN
D000085:Acetates / Q000378:metabolism*; D000588:Amines; D000818:Animals; D000927:Anticonvulsants / Q000378:metabolism*; D015220:Calcium Channels / Q000302:isolation & purification* / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism*; D002522:Chlorocebus aethiops; D002845:Chromatography; D002846:Chromatography, Affinity; D002850:Chromatography, Gel; D002852:Chromatography, Ion Exchange; D003509:Cyclohexanecarboxylic Acids; D018076:DNA, Complementary; D017886:Durapatite; D004591:Electrophoresis, Polyacrylamide Gel; D000077206:Gabapentin; D007700:Kinetics; D046911:Macromolecular Substances; D008970:Molecular Weight; D018482:Muscle, Skeletal / Q000378:metabolism*; D011817:Rabbits; D011994:Recombinant Proteins / Q000378:metabolism; D013552:Swine; D014162:Transfection; D014316:Tritium; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000927:Anticonvulsants; D015220:Calcium Channels; D003509:Cyclohexanecarboxylic Acids; D018076:DNA, Complementary; D046911:Macromolecular Substances; D011994:Recombinant Proteins; D014316:Tritium; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin; D017886:Durapatite