Apamin isaneurotoxinthatwasoriginallyisolatedfromApismellifera.Apaminbindstoandinhibitsthe SKchannels(smallconductanceCa2+-activatedK+ channels) inthebrainandspinalcord. Apamin inhibitsthreesubtypesof SKchannels(KCa2.1,KCa2.2,andKCa2.3) withdifferentaffinity. Apamin doesnotaffectKCa3.1channelactivity. Apaminmostlikelyactsasaporeblockersuchas Scyllatoxin or Tamapin,althoughresiduesbothinsideandoutsideoftheporeregionoftheSKchannelsparticipateinapaminbinding.TheSKchannelsarepresentinawiderangeofexcitableandnon-excitablecells,includingcellsinthecentralnervoussystem,intestinalmyocytes,endothelialcells,andhepatocytes.
Description:
AAsequence: H-Cys1-Asn-Cys3-Lys-Ala-Pro-Glu-Thr-Ala-Leu-Cys11-Ala-Arg-Arg-Cys15-Gln-Gln-His-NH2
Disulfidebonds: Cys1-Cys11 andCys3-Cys15
Length(aa): 18
Formula: C79H131N31O24S4
MolecularWeight: 2027.34Da
Appearance: Whitelyophilizedsolid
Solubility: waterandsalinebuffer
CASnumber: [24345-16-2]Source: Synthetic
Purityrate: >98%
Reference:
Apamin
Potassiumchanneltoxins
Manyvenomtoxinsinterferewithionchannelfunction.Toxins,asspecific,highaffinityligands,haveplayedanimportantpartinpurifyingandcharacterizingmanyionchannelproteins.Ourknowledgeofpotassiumionchannelstructureismeagerbecauseuntilrecently,nospecificpotassiumchanneltoxinswereknown,oridentifiedassuch.Thisreviewsummarizesthesuddenexplosionofresearchonpotassiumchanneltoxinsthathasoccurredinrecentyears.Toxinsarediscussedintermsoftheirstructure,physiologicalandpharmacologicalproperties,andthecharacterizationoftoxinbindingsitesondifferentsubtypesofpotassiumionchannels.
StrongPN(1990).Potassiumchanneltoxins. PharmacolTher. PMID:2181489
Toxinsinthecharacterizationofpotassiumchannels
Severalrecentlycharacterizedtoxins(apamin,charyBDotoxin,dendrotoxinandnoxiustoxin)areprovinginvaluableforestablishingwhatkindsofpotassiumchannelareexpressedinneurones,andwhattherolesofthechannelsmightbe.
CastleNA.etal.(1989).Toxinsinthecharacterizationofpotassiumchannels. TrendsNeurosci. PMID:2469212
