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Ectatomin
From Proteopedia
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Ectatomin is a highly basic toxin and contains <scene name='84/841096/Scene_2/1'> two homologous polypeptide chains linked to each other by a disulfide bond.</scene> <scene name='84/841096/Scene_3/3'>The two anti-parallel alpha helical chains consist of 37 and 34 amino acid residues</scene> with an <scene name='84/841096/Disulfide_bridge/1'>internal disulfide bridge</scene> in each chain that forms a hairpin. In aqueous solution ectatomin forms a four-alpha helix bundle. | Ectatomin is a highly basic toxin and contains <scene name='84/841096/Scene_2/1'> two homologous polypeptide chains linked to each other by a disulfide bond.</scene> <scene name='84/841096/Scene_3/3'>The two anti-parallel alpha helical chains consist of 37 and 34 amino acid residues</scene> with an <scene name='84/841096/Disulfide_bridge/1'>internal disulfide bridge</scene> in each chain that forms a hairpin. In aqueous solution ectatomin forms a four-alpha helix bundle. | ||
== Channel Formation == | == Channel Formation == | ||
| - | Ectatomin has channel-forming activity. It forms nonselective cation channels in membrane systems and the channel formation depends on membrane potentials and occurs only at a positive cis-potential. Each pore is formed by two ectatomin molecules. This channel-forming property of ectatomin may account partially for its toxic activity. The high level of ectatomin’s toxicity implies that there may be specific cellular targets for its action. | + | Ectatomin has channel-forming activity. It forms nonselective cation channels in membrane systems and the channel formation depends on membrane potentials and occurs only at a positive cis-potential. Each pore is formed by two ectatomin molecules. This channel-forming property of ectatomin may account partially for its toxic activity. The high level of ectatomin’s toxicity implies that there may be specific cellular targets for its action. <ref>Silva, Juliana Rocha da, et al. “Assessing the Proteomic Activity of the Venom of the Ant Ectatomma Tuberculatum (Hymenoptera: Formicidae: Ectatomminae).” Psyche: A Journal of Entomology, June 2018, pp. 1–11. EBSCOhost, doi:10.1155/2018/7915464.</ref> |
Many pore forming toxins have similar mechanisms. The toxin recognizes the cell membrane by either a specific receptor or by the direct interactions with the membrane lipids. After the toxin binds with the cell membrane, the protein undergoes a considerable conformational change to form the pore. | Many pore forming toxins have similar mechanisms. The toxin recognizes the cell membrane by either a specific receptor or by the direct interactions with the membrane lipids. After the toxin binds with the cell membrane, the protein undergoes a considerable conformational change to form the pore. | ||
| - | Ectatomin is inserted effectively and efficiently into the plasma membrane at a concentration of 5 x 10-7 M and does not penetrate through the cell membranes. | + | Ectatomin is inserted effectively and efficiently into the plasma membrane at a concentration of 5 x 10-7 M and does not penetrate through the cell membranes.<ref>Pluzhnikov, K., et al. “Analysis of Ectatomin Action on Cell Membranes.” European Journal Of Biochemistry, vol. 262, no. 2, June 1999, pp. 501–506. EBSCOhost, search.ebscohost.com/login.aspx?direct=true&db=mdc&AN=10336635&site=eds-live&scope=site.</ref> |
== Hemolytic and Cytolytic Effects == | == Hemolytic and Cytolytic Effects == | ||
Hemolytic activities of ectatomin were determined in rabbit erythrocytes with 78 HU*mg-1 and 41 HU*mg-1 . The cytolytic activity of ectatomin was observed in Sf9 cells and was (2 +/- 0.8) x 10-6 M. These hemolytic and cytolytic effects are seen at high concentrations (0.5 x 10-6 to 10-5). At these high concentrations, ectatomin damages cell membranes in a detergent-like or pore-forming fashion. This supports that the binding of the ectatomin to cell membranes is nondescriminative; it involves lipids rather than specific receptor molecules. | Hemolytic activities of ectatomin were determined in rabbit erythrocytes with 78 HU*mg-1 and 41 HU*mg-1 . The cytolytic activity of ectatomin was observed in Sf9 cells and was (2 +/- 0.8) x 10-6 M. These hemolytic and cytolytic effects are seen at high concentrations (0.5 x 10-6 to 10-5). At these high concentrations, ectatomin damages cell membranes in a detergent-like or pore-forming fashion. This supports that the binding of the ectatomin to cell membranes is nondescriminative; it involves lipids rather than specific receptor molecules. | ||
Revision as of 03:03, 29 April 2020
Introduction
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