Description
ThepresenceofCysteine26inWheatgerm(Triticumaestivum)calmodulin(CaM)makesituniquevis-a-vismammaliancalmodulin.IncontrasttomammalianCaMs,whichlackcysteine,thispreparationisidealforapplicationsrequiringbothcalmodulinactivationandresiduespecifictagging.Mono-taggedBiotinylatedlabeledwheatgermcalmodulinatpositionCysteine26isusefulforproteinarrayapplicationsforthedetectionofcalmodulinbindingproteins(CBPs),Westernblotsandotherapplicationsrequiringaconvenientandsuperiorfluorescentlylabeledcalmodulin.Calmodulin(CaM)isaubiquitous,calcium-bindingproteinthatbindsandregulatesamultitudeofproteintargets,manyofwhichareinvolvedintheAlzheimer"sandtheParkinson"spathways1,4.CaMhasamolecularweightofabout17kDa,containing148aminoacids,andpIof3.9.CaMischaracterizedbytwodomains,connectedbyanalpha-helixchain.Eachdomainhasthecapacitytobindtwocalciumions.BindingCa2+ionscausesaconformationalchangeinCaM,makingitavailableforinteractionwithtargetproteins.Hence,CaMfunctionsasanintracellularcalciumionbridgetomediatecellularreactionsandrespondsappropriatelytocalciumionconcentration.InAlzheimer"sdisease(AD),irregularcalciumhomeostasisseemstotriggerCaManditsbindingproteins,toenhanceplaqueformationandneurofibrillarydegeneration,whichresultsincelldeath1.TheincreasedcytosoliclevelsofCa2+inADneuronspromotesCaMbindingandregulationofavailableCa2+/CaM-dependentCaM-bindingproteins,associatedwithamyloidbeta(Ab)formation.Inaddition,theincreasedlevelofCa2+triggersCalmodulintoactivatecalcium/CaM-dependentkinaseIIandprecedeneurofibrillarytangleformation2,4.InParkinson"sdisease(PD),Calmodulinhasbeenfoundtointeract,inacalciumdependentmanner,withAlpha-Synuclein,whichisassociatedwiththeprogressionofPD.CaMwasidentifiedasoneofthesynuclein-interactingproteinsthatregulatesynucleinconformation3.