Molecular diversity of Ca2+ channel alpha 1 subunits from the marine ray Discopyge ommata.
In many neurons, transmitter release from presynaptic terminals is triggered by Ca2+ entry via dihydropyridine-insensitive Ca2+ channels. We have looked for cDNAs for such channels in the nervous system of the marine ray Discopyge ommata. One cDNA (doe-2) is similar to dihydropyridine-sensitive L-type channels, and two cDNAs (doe-1 and doe-4) are similar to the subfamily of dihydropyridine-insensitive non-L-type channels. doe-4, which encodes a protein of 2326 aa, most closely resembles a previously cloned N-type channel. doe-1, which encodes a protein of 2223 aa, is a member of a separate branch of the non-L-type channels. Northern blot analysis reveals that doe-1 is abundant in the forebrain. doe-4 is more plentiful in the electric lobe and, therefore, may control neurotransmitter release in motor nerve terminals. These results show that the familial pattern of Ca(2+)-channel genes has been preserved from a stage in evolution before the divergence of higher and lower vertebrates > 400 million years ago. The cloning of these channels may be a useful starting point for elucidating the role of the Ca2+ channels in excitation-secretion coupling in nerve terminals.
Horne
W A
WA
Department of Molecular and Cellular Physiology, Stanford University Medical Center, CA 94305.
Ellinor
P T
PT
Inman
I
I
Zhou
M
M
Tsien
R W
RW
Schwarz
T L
TL
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D015220:Calcium Channels / Q000235:genetics*; D003001:Cloning, Molecular / Q000379:methods; D004247:DNA / Q000235:genetics / Q000302:isolation & purification; D004557:Electric Organ / Q000502:physiology*; D014644:Genetic Variation; D046911:Macromolecular Substances; D008322:Mammals; D008969:Molecular Sequence Data; D009046:Motor Neurons / Q000502:physiology; D005810:Multigene Family; D009411:Nerve Endings / Q000502:physiology; D009928:Organ Specificity; D010446:Peptide Fragments / Q000737:chemistry; D010802:Phylogeny; D011061:Poly A / Q000235:genetics / Q000302:isolation & purification; D016133:Polymerase Chain Reaction / Q000379:methods; D016548:Prosencephalon / Q000502:physiology*; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger; D017386:Sequence Homology, Amino Acid; D012860:Skates, Fish; D014158:Transcription, Genetic
D015220:Calcium Channels; D046911:Macromolecular Substances; D010446:Peptide Fragments; D012333:RNA, Messenger; D011061:Poly A; D012313:RNA; D004247:DNA