Why do hormone receptors arise? An introduction.- The evolution of recognition.- Signal receivers and signal molecules.- Interrelation of hormone receptor evolution.- Conclusions.- Mechanisms of receptor-mediated transmembrane signaling.- Receptors, acceptors channels and the problem of transmembrane-signaling.- General mechanisms of transmembrane signaling.- Receptor dynamics and transmembrane signaling.- Receptor microclustering and cell activation.- Internalized receptor and cell activation.- Summary.- Insulin receptors: structure and function.- The molecular mechanism of insulin action.- The insulin receptor kinase.- Biochemical properties of the insulin receptor kinase.- Role of receptor phosphorylation in insulin action.- Structure-function relationship of the insulin receptor kinase.- Summary and conclusions.- Internalization of polypeptide hormones and receptor recycling.- Historical perspective.- Events at the cell surface (steps 1, 2 and 3).- Initial steps of endocytosis (steps 4 and 5).- Later steps of endocytosis (steps 6, 7 and 8).- Receptor recycling.- What determines the specificity of receptor-mediated endocytosis.- Biochemical features of receptor-mediated endocytosis.- Functional implications of receptor-mediated endocytosis.- Conclusions.- The nature and development of steroid hormone receptors.- Models of steroid hormone action.- Nuclear binding sites.- Development of steroid receptors: Ontogeny of estrogen receptors.- Receptor ontogeny and hormonal imprinting.- Receptor alterations during ontogenetic development.- Why is receptor adaptation necessary? An approach based on information theory.- Experimental evidence for hormonal imprinting.- Polypeptide hormones.- Imprinting by related hormones; the disturbing effect of noise.- Overlapping imprinting by steroid hormones.- Imprinting with acid type hormones.- The importance and sensitivity of imprinting.- Hormonal imprinting in cell lines.- Cell-cell transmission of hormonal imprinting.- HormonallS#