Molecular Cloning and Characterization of a Putative Neural Calcium Channel α1-Subunit from Squid Optic Lobe

Kimura, Tadashi; Shouno, Osamu; Hirota, Kiyonori; Saito, Takehiko; Matsumoto, Gen; Sato, Chikara

doi:10.1006/bbrc.1996.5732

Cited by 8 publications

(2 citation statements)

References 21 publications

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“…Scale bar, 500 substitutions. The Ca 2+ channel α1 subunit sequences are as follows: BgCa v 1 (Blattella germanica, German cockroach, GenBank accession number D31719), BgCa v 2 (Blattella germanica, GenBank accession number D31718), CcCa v 1 (Cyanea capillata, Scyphozoan jellyfish [Jeziorski et al, 1998]), DmCa v A1 (Drosophila melanogaster, [Eberl et al, 1998]), DmCa v D1 (Drosophila melanogaster, [Smith et al, 1996]), LbCa v 1 (Loligo bleekeri, squid [Kimura et al, 1997]), MdCa v 1 (Musca domestica, house fly [Grabner et al, 1994]). The invertebrate Na + channel and Na + channel-related sequences are from the following species: ApNa v 1 (Aiptasia pallida, sea anemone), BgNa v 1 (Blattella germanica, para CSMA ), BSC1 (Blattella germanica), CcNa v 1 (Cyanea capillata, CYNA1), DmNa v 1 (Drosophila melanogaster, para), DSC1 (Drosophila melanogaster), LbNa v 1 (Loligo bleekeri, squid Na channel), LoNa v 1 (Loligo opalescens, GFLN1), MdNa v 1 (Musca domestica, Msc Vssc1), and PpNa v 1 (Polyorchis penicillatus, Hydrozoan jellyfish, PpSCN1).…”

Section: Figure 5 Substitution Of E1497 With K Reduces the Selectivimentioning

confidence: 99%

A Voltage-Gated Calcium-Selective Channel Encoded by a Sodium Channel-like Gene

Zhou

Chung

Liu

et al. 2004

Neuron

108

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BSC1, which was originally identified by its sequence similarity to voltage-gated Na(+) channels, encodes a functional voltage-gated cation channel whose properties differ significantly from Na(+) channels. BSC1 has slower kinetics of activation and inactivation than Na(+) channels, it is more selective for Ba(2+) than for Na(+), it is blocked by Cd(2+), and Na(+) currents through BSC1 are blocked by low concentrations of Ca(2+). All of these properties are more similar to voltage-gated Ca(2+) channels than to voltage-gated Na(+) channels. The selectivity for Ba(2+) is partially due to the presence of a glutamate in the pore-forming region of domain III, since replacing that residue with lysine (normally present in voltage-gated Na(+) channels) makes the channel more selective for Na(+). BSC1 appears to be the prototype of a novel family of invertebrate voltage-dependent cation channels with a close structural and evolutionary relationship to voltage-gated Na(+) and Ca(2+) channels.

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Section: Figure 5 Substitution Of E1497 With K Reduces the Selectivimentioning

confidence: 99%

A Voltage-Gated Calcium-Selective Channel Encoded by a Sodium Channel-like Gene

Zhou

Chung

Liu

et al. 2004

Neuron

108

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“…A putative Ca 2+ channel clone has also been reported from squid [111]. Like the Na + channel SQNC1, this clone, SQCC1, was isolated from an optic lobe cDNA library, and Northern blots verified expression of its mRNA in the stellate ganglion, but not specifically in GFL neurons.…”

Section: Molecular Candidates For Calcium Conductancementioning

confidence: 99%

Identified Ion Channels in the Squid Nervous System

Rosenthal

Gilly²

2003

Neurosignals

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Our modern understanding of channels as discrete voltage-sensitive and ion-selective entities comes largely from a series of classical studies using the squid giant axon. This system has also been critical for understanding how transporters and synaptic transmission operate. This review outlines attempts to assign molecular identities to the extensively studied physiological properties of this system. As it turns out, this is no simple task. Molecular candidates for voltage-gated Na⁺, K⁺, and Ca²⁺ channels, as well as ion transporters have been isolated from the squid nervous system. Both physiological and molecular approaches have been used to equate these cloned gene products with their native counterparts. In the case of the delayed rectifier K⁺ conductance, the most thoroughly studied example, two major issues further complicate the equation. First, the ability of K⁺ channel monomers to form heteromultimers with unique properties must be considered. Second, squid K⁺ channel mRNAs are extensively edited, a process that can generate a wide variety of channel proteins from a common gene. The giant axon system is beginning to play an important role in understanding the biological relevance of this latter process.

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