identifyandisolateitsantigen-bindingreceptor.Theobvi-ousparallelsbetweentherecognitionfunctionsofTcellsandBcellsstimulatedagreatdealofexperimentalefforttotakeadvantageoftheanticipatedstructuralsimilaritiesbe-tweenimmunoglobulinsandT-cellreceptors.Reportspublishedinthe1970sclaimeddiscoveryofimmunoglob-ulinisotypesassociatedexclusivelywithTcells(IgT)andofantiserathatrecognizevariable-regionmarkers(idio-types)commontoantibodiesandT-cellreceptorswithsimilarspecificity.Theseexperimentscouldnotberepro-ducedandwereproventobeincorrectwhenitwasdemon-stratedthattheT-cellreceptorandimmunoglobulinsdonothavecommonrecognitionelementsandareencodedbyentirelyseparategenefamilies.Asthefollowingsectionswillshow,asequenceofwell-designedexperimentsusingcutting-edgetechnologywasrequiredtocorrectlyanswerquestionsaboutthestructureoftheT-cellreceptor,thegenesthatencodeit,andthemannerinwhichitrecognizesantigen.chapter9IEarlyStudiesoftheT-CellReceptorI��and��T-CellReceptors:StructureandRolesIOrganizationandRearrangementofTCRGenesIT-CellReceptorComplex:TCR-CD3IT-CellAccessoryMembraneMoleculesIThree-DimensionalStructuresofTCR-Peptide-MHCComplexesIAlloreactivityofTCellsT-CellReceptorT--clearlyimpliesthatTcellspossessanantigen-specificandclonallyrestrictedreceptor.However,theidentityofthisreceptorremainedunknownlongaftertheB-cellreceptor(immunoglobulinmolecule)hadbeenidentified.RelevantexperimentalresultswerecontradictoryanddifficulttoconceptualizewithinasinglemodelbecausetheT-cellreceptor(TCR)differsfromtheB-cellantigen-bindingreceptorinimportantways.First,theT-cellreceptorismembraneboundanddoesnotappearinasolubleformastheB-cellreceptordoes;therefore,assessmentofitsstruc-turebyclassicbiochemicalmethodswascomplicated,andcomplexcellularassayswerenecessarytodetermineitsspeci-ficity.Second,mostT-cellreceptorsarespecificnotforanti-genalonebutforantigencombinedwithamoleculeencodedbythemajorhistocompatibilitycomplex(MH...
