acetylcholine bindingsites bindingsites(biochemistry) biochemistry cellreceptors cellsurface cellularrecognition congresses immunologic immunospecificity molecularrecognition plantcellinteraction planthormones proteinbinding qu4a2851978m qu4a285m1978 receptors sensoryreceptorcells steroid steroidhormones w3ah2856th1978m wk102e931982 wk150m9611977