Molecular analysis and functional expression of the human type E neuronal Ca2+ channel alpha 1 subunit.
A human brain alpha 1 Ca2+ channel subunit was cloned and expressed in Xenopus laevis oocytes. The open reading frame, encoding 2,312 amino acids, has high homology to the marine ray doe-1, the rat E-type, and the rabbit brain BII alpha 1 subunits. The amino and carboxy termini of this human.E-type alpha 1 subunit (alpha 1E) are most similar to the rabbit BII-1 splice variant, the remainder being colinear with the BII alpha 1 with the exception of two insertions, one of 43 amino acids in the C-terminus and another of 7 amino acids, found also in the rat alpha 1E, between domains II and III. Two potential Ca2+ binding sites are predicted from its primary structure. The expression of inward Ba2+ currents reveals voltage-dependent activation and inactivation measured by the cut-open oocyte vaseline-gap technique, with kinetics that correspond to that of a high-voltage-activated neuronal Ca2+ channel, and pharmacologic properties that resemble those of some low-voltage-activated neuronal Ca2+ currents. The human alpha 1E currents are insensitive to omega-conotoxin-GVIA (1 microM), omega-agatoxin-IVA (200 nM), a synthetic funnel web spider toxin (FTX, 20 microM), and Bay-K8644 (0.5 microM); they are inhibited 20% by high concentrations of methoxyverapamil and diltiazem, 65% by 0.1% crude funnel web spider venom and 100% by Ni2+ (IC50 = 30 nM). Single-channel records show a complex activity pattern with several apparent conductance states, the largest having a conductance of 14 pS.
Schneider
T
T
Division of Neuroscience, Baylor College of Medicine, Houston, TX 77030.
Wei
X
X
Olcese
R
R
Costantin
J L
JL
Neely
A
A
Palade
P
P
Perez-Reyes
E
E
Qin
N
N
Zhou
J
J
Crawford
G D
GD
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001464:Barium / Q000494:pharmacology; D001483:Base Sequence; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000096:biosynthesis* / Q000737:chemistry / Q000502:physiology; D020908:Calcium Channels, R-Type; D027682:Cation Transport Proteins; D003001:Cloning, Molecular; D017931:DNA Primers; D004110:Diltiazem / Q000494:pharmacology; D005260:Female; D005711:Gallopamil / Q000494:pharmacology; D015870:Gene Expression; D014644:Genetic Variation; D006801:Humans; D007700:Kinetics; D046911:Macromolecular Substances; D008564:Membrane Potentials / Q000187:drug effects; D008969:Molecular Sequence Data; D009474:Neurons / Q000378:metabolism*; D009532:Nickel / Q000494:pharmacology; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D010455:Peptides / Q000494:pharmacology; D011073:Polyamines / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D011817:Rabbits; D051381:Rats; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid; D012860:Skates, Fish; D013111:Spider Venoms / Q000494:pharmacology; D014982:Xenopus laevis; D020867:omega-Agatoxin IVA; D020866:omega-Conotoxin GVIA
C423009:CACNA1E protein, human; C498917:Cacna1e protein, rat; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D020908:Calcium Channels, R-Type; D027682:Cation Transport Proteins; D017931:DNA Primers; C071920:FTX, spider toxin; D046911:Macromolecular Substances; D010455:Peptides; D011073:Polyamines; D013111:Spider Venoms; D020867:omega-Agatoxin IVA; D001464:Barium; D005711:Gallopamil; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D009532:Nickel; D020866:omega-Conotoxin GVIA; D004110:Diltiazem; D002118:Calcium