Topic
Torpedo
About: Torpedo is a research topic. Over the lifetime, 579 publications have been published within this topic receiving 26622 citations.
Papers published on a yearly basis
1 / 2
Papers
TL;DR: The single-channel conductance properties of these AChR mutants expressed in Xenopus laevis oocytes indicate that three clusters of negatively charged and glutamine residues neighbouring segment M2 of the α-, β-, γ- and δ-subunits, probably forming three anionic rings, are major determinants of the rate of ion transport.
Abstract: The structure-function relationship of the nicotinic acetylcholine receptor (AChR) has been effectively studied by the combination of complementary DNA manipulation and single-channel current analysis. Previous work with chimaeras between the Torpedo californica and bovine AChR delta-subunits has shown that the region comprising the hydrophobic segment M2 and its vicinity contains an important determinant of the rate of ion transport through the AChR channel. It has also been suggested that this region is responsible for the reduction in channel conductance caused by divalent cations and that segment M2 contributes to the binding site of noncompetitive antagonists. To identify those amino acid residues that interact with permeating ions, we have introduced various point mutations into the Torpedo AChR subunit cDNAs to alter the net charge of the charged or glutamine residues around the proposed transmembrane segments. The single-channel conductance properties of these AChR mutants expressed in Xenopus laevis oocytes indicate that three clusters of negatively charged and glutamine residues neighbouring segment M2 of the alpha-, beta-, gamma- and delta-subunits, probably forming three anionic rings, are major determinants of the rate of ion transport.
811 citations
TL;DR: The results show the nicotinic acetylcholine receptor from Torpedo electric fish to have a pentameric structure with a central water‐filled pore, which can now be said to be characteristic of the entire superfamily.
Abstract: In the transmitter-gated ion channel class of receptors, the members of which are all believed to be heterooligomers, the number and arrangement of the subunits are only known with any certainty for the nicotinic acetylcholine receptor from Torpedo electric fish. That receptor has been shown to possess a pentameric rosette structure, with five homologous subunits (alpha 2, beta gamma delta) arranged to enclose the central ion channel. The data were obtained by electron image analysis of two-dimensional receptor arrays, which form as a consequence of that receptor's exceptionally high abundance in the Torpedo membranes and are therefore not attainable for other receptors. We have applied another direct approach to determine the quaternary structure of native ionotropic GABA receptors. We have purified those receptors from porcine brain cortex and analysed the rotational symmetry of isolated receptors visualized by electron microscopy. The results show the receptor to have a pentameric structure with a central water-filled pore, which can now be said to be characteristic of the entire superfamily.
446 citations
TL;DR: The complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone is reported and the 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin8.
Abstract: Acetylcholinesterase, an essential enzyme of the nervous system, rapidly terminates the action of acetylcholine released into the synapse. Acetylcholinesterase is also found (in lower abundance) in extrajunctional areas of muscle and nerve and on erythrocyte membranes. Hydrodynamic analyses of the native enzyme and characterization of its dissociated subunits have revealed multiple enzyme forms which can be divided into two classes: dimensionally asymmetric forms which are usually found within the synapse and contain a collagen-like structural subunit disulphide-linked to the catalytic subunits; and globular forms which appear to be widely distributed on the outer surface of cell membranes. Both forms have been characterized in the ray Torpedo californica and, although their catalytic behaviours seem to be identical, they differ slightly in amino-acid composition, peptide maps and reactivity with certain monoclonal antibodies. Here, we report the complete amino-acid sequence of an acetylcholinesterase inferred from the sequence of a complementary DNA clone. The 575-residue protein shows significant homology with the C-terminal portion of thyroglobulin.
442 citations
1 Jan 2016
TL;DR: The unexpected similarities between alpha and beta and between gamma and delta subunits raise the possibility that the complex four-subunit structure of AcChoR was derived from a simpler precursor and suggests that these antigenic similarities might reflect some structural and functional homologies.
Abstract: Seventeen cell lines producing monoclonal antibodies against Torpedo californica (torpedo) acetylcholine receptor (AcChoR) and its subunits were established. By using these antibodies as probes, we identified: (i) a similar antigenic determinant on a and 3 torpedo subunits, (ii) a similar antigenic determinant on y and a subunits, (iii) antigenic determinants unique for a or 3 torpedo AcChoR subunits, (iv) a small region on the a! subunit that dominates the immunogenicity of native torpedo AcChoR in rats (a monoclonal antibody directed at this region could bind to rat AcChoR in vivo and cause passive ex- perimental autoimmune myasthenia gravis), and (v) antigenic determinants on torpedo subunits recognized in AcChoR from other species. The unexpected similarities between a and a and between y and a subunits raise the possibility that the complex four-subunit structure of AcChoR was derived from a simpler precursor and suggests that these antigenic similarities might reflect some structural and functional homologies. Acetylcholine receptor (AcChoR) from the electric organs of Torpedo californica (torpedo) and Electrophorus electricus
391 citations
TL;DR: Cloned and sequenced DNA complementary to the Torpedo californica electroplax messenger RNA encoding the α-subunit of (Na+ + K+)ATPase is cloned and deduced the complete ammo-acid sequence of the polypeptide.
Abstract: Sodium- and potassium-dependent ATPase [(Na+ + K+)ATPase], which is responsible for the active transport of Na+ and K+, is distributed universally among animal cell membranes and consists of two types of subunits, α and β (refs 1–4). The larger α-subunit with a relative molecular mass (Mr) of 84,000–120,000 is thought to have the catalytic role. We have now cloned and sequenced DNA complementary to the Torpedo californica electroplax messenger RNA encoding the α-subunit of (Na+ + K+)ATPase and have deduced the complete ammo-acid sequence of the polypeptide. Some structural features of the α-subunit molecule related to the function of this active-transport protein are discussed.
372 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2025 | 14 |
| 2024 | 21 |
| 2023 | 37 |
| 2022 | 28 |
| 2021 | 7 |
| 2020 | 4 |