n. (context biochemistry English) A neurotoxin originally isolated from ''Apis mellifera'', the Western honey bee.
Apamin is an 18 amino acid peptide neurotoxin found in apitoxin ( bee venom). Dry bee venom consists of 2-3% of apamin. Apamin selectively blocks SK channels, a type of Ca-activated K channel expressed in the central nervous system. Toxicity is caused by only a few amino acids, these are cysteine, lysine, arginine, arginine and histidine. These amino acids are involved in the binding of apamin to the Ca-activated K channel. Due to its specificity for SK channels, apamin is used as a drug in biomedical research to study the electrical properties of SK channels and their role in the afterhyperpolarizations occurring immediately following an action potential.