Molecular analysis and functional expression of the human type E neuronal Ca2+ channel alpha 1 subunit

Recept Channels. 1994;2(4):255-70.

Abstract

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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / pharmacology
  • Alternative Splicing
  • Amino Acid Sequence
  • Animals
  • Barium / pharmacology
  • Base Sequence
  • Binding Sites
  • Brain / metabolism*
  • Calcium / metabolism
  • Calcium Channel Blockers / pharmacology
  • Calcium Channels / biosynthesis*
  • Calcium Channels / chemistry
  • Calcium Channels / physiology
  • Calcium Channels, R-Type
  • Cation Transport Proteins*
  • Cloning, Molecular
  • DNA Primers
  • Diltiazem / pharmacology
  • Female
  • Gallopamil / pharmacology
  • Gene Expression*
  • Genetic Variation
  • Humans
  • Kinetics
  • Macromolecular Substances
  • Membrane Potentials / drug effects
  • Molecular Sequence Data
  • Neurons / metabolism*
  • Nickel / pharmacology
  • Oocytes / drug effects
  • Oocytes / physiology*
  • Peptides / pharmacology
  • Polyamines / pharmacology
  • Polymerase Chain Reaction
  • Rabbits
  • Rats
  • Restriction Mapping
  • Sequence Homology, Amino Acid
  • Skates, Fish
  • Spider Venoms / pharmacology
  • Xenopus laevis
  • omega-Agatoxin IVA
  • omega-Conotoxin GVIA

Substances

  • CACNA1E protein, human
  • Cacna1e protein, rat
  • Calcium Channel Blockers
  • Calcium Channels
  • Calcium Channels, R-Type
  • Cation Transport Proteins
  • DNA Primers
  • FTX, spider toxin
  • Macromolecular Substances
  • Peptides
  • Polyamines
  • Spider Venoms
  • omega-Agatoxin IVA
  • Barium
  • Gallopamil
  • 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester
  • Nickel
  • omega-Conotoxin GVIA
  • Diltiazem
  • Calcium

Associated data

  • GENBANK/L27745