Tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunit subtypes.
We report here the tissue-specific expression and gabapentin-binding properties of calcium channel alpha2delta subunits. Northern blot analysis demonstrated that human alpha2delta-1, -2, and -3 mRNA all had high levels of expression in brain, heart and skeletal muscle. However, the highest expression of human alpha2delta-2 mRNA was found in lung. Human alpha2delta-1, -2, and -3 mRNAs were detected in all portions of brain tested. Western blotting revealed that alpha2delta-2 protein was predominantly expressed in cerebellar cortex (brain) and undetectable in lung. The dissociation between mRNA and protein levels of human alpha2delta-2 in lung suggests possible post-transcriptional regulation. Although mouse alpha2delta-1 proteins exhibited a similar tissue distribution profile as that of human, tissue distribution of mouse alpha2delta-2 and -3 mRNA revealed a different profile. Mouse alpha2delta-3 mRNA was restricted to brain and mouse alpha2delta-2 mRNA was not detectable in lung. Gel electrophoresis under a reduced condition resulted in a mobility shift of both alpha2delta-1 and alpha2delta-2 proteins, suggesting that alpha2 and delta of alpha2delta-2 protein are linked by disulfide bond as are alpha2 and delta of alpha2delta-1. Scatchard plots revealed a single population of gabapentin binding sites for human alpha2delta-2 with the KD value twofold higher than that of porcine alpha2delta-1 (156 +/- 25 nm vs. 72 +/- 9 nm). Inhibition of gabapentin binding to alpha2delta-2 by selected amino acids and gabapentin analogs produced a binding profile similar, but not identical to that of alpha2delta-1.
Gong
H C
HC
Department of Molecular Sciences, Pfizer Global Research and Development, Ann Arbor, MI 48105, USA.
Hang
J
J
Kohler
W
W
Li
L
L
Su
T Z
TZ
D000085:Acetates / Q000378:metabolism*; D000588:Amines; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D000927:Anticonvulsants / Q000378:metabolism; D001665:Binding Sites; D015220:Calcium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002460:Cell Line; D003509:Cyclohexanecarboxylic Acids; D000077206:Gabapentin; D006801:Humans; D051379:Mice; D011485:Protein Binding; D020033:Protein Isoforms; D017433:Protein Structure, Secondary; D021122:Protein Subunits; D011869:Radioligand Assay; D014018:Tissue Distribution; D005680:gamma-Aminobutyric Acid
D000085:Acetates; D000588:Amines; D000596:Amino Acids; D000927:Anticonvulsants; D015220:Calcium Channels; D003509:Cyclohexanecarboxylic Acids; D020033:Protein Isoforms; D021122:Protein Subunits; D005680:gamma-Aminobutyric Acid; D000077206:Gabapentin