acetylcholine bindingsites bindingsites(biochemistry) biochemistry cellcommunication cellreceptors cellsurface cellular cellularimmunity congresses genes hormonereceptors immuneresponse immunity immunologic immunospecificity mhcclassii molecularbiology molecularrecognition morphology proteinbinding proteins qu34b6141979 qu4a2851978m qu4a285m1978 qw568r3111985 receptors regulation sensoryreceptorcells viruses w3ah2856th1978m