Cell-surface receptors 1. Process of transmembrane signal transduction a Synthesis and secretion of signaling molecules a Receptor binding and initiation of intracellular signaling pathway a Regulation of cellular metabolism, function, gene expression, etc a Down-regulation or termination of cellular responses EXTRACELLULAR SIGNAL MOLECULE RECEPTOR PROTEIN CYTOPLASM FLUID REception 2 Transduction 3 Respo Recepto INTRACELLULAR SIGNALING PROTEINS Signal-transduction pathway molecule Plasma membrane 83 TARGET PROTEINS altered altered cel movement1. Process of transmembrane signal transduction Cell-surface receptors  Synthesis and secretion of signaling molecules  Receptor binding and initiation of intracellular signaling pathway  Regulation of cellular metabolism, function, gene expression, etc  Down-regulation or termination of cellular responses