| Melittin | |||||||||
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 Melittin 
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| Identifiers | |||||||||
| Symbol | Melittin | ||||||||
| Pfam | PF01372 | ||||||||
| InterPro | IPR002116 | ||||||||
| SCOP | 2mlt | ||||||||
| SUPERFAMILY | 2mlt | ||||||||
| TCDB | 1.C.18 | ||||||||
| OPM superfamily | 160 | ||||||||
| OPM protein | 2mlt | ||||||||
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| Available protein structures: | |
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| Pfam | structures | 
| PDB | RCSB PDB; PDBe; PDBj | 
| PDBsum | structure summary | 
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 3D model (Jmol) 
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.157.496 | 
| MeSH | Melitten | 
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PubChem CID
 
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| Properties | |
| C131H229N39O31 | |
| Molar mass | 2846.46266 | 
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 Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). 
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| Infobox references | |
Melittin is the principal active component of apitoxin (bee venom) and is a powerful stimulator of phospholipase A2. Melittin is a peptide consisting of 26 amino acids with the sequence GIGAVLKVLTTGLPALISWIKRKRQQ.
Melittin inhibits protein kinase C, Ca2+/calmodulin-dependent protein kinase II, myosin light chain kinase and Na+/K+-ATPase (synaptosomal membrane) and is a cell membrane lytic factor. Melittin is a small peptide with no disulfide bridge; the N-terminal part of the molecule is predominantly hydrophobic and the C-terminal part is hydrophilic and strongly basic.
Extensive work with melittin has shown that the venom has multiple effects, probably, as a result of its interaction with negatively charged phospholipids. It inhibits well known transport pumps such as the Na+-K+-ATPase and the H+-K+-ATPase. Melittin increases the permeability of cell membranes to ions, particularly Na+ and indirectly Ca2+, because of the Na+-Ca2+-exchange. This effect results in marked morphological and functional changes, particularly in excitable tissues such as cardiac myocytes. In some other tissues, e.g., cornea, not only Na+ but Cl− permeability is also increased by melittin. Similar effects to melittin on H+-K+-ATPase have been found with the synthetic amphipathic polypeptide Trp-3.