[Cell receptors: major concepts].

There are two large categories of cell receptors, nuclear receptors and membrane receptors. Nuclear receptors are activated by steroid hormones and vitamin A. They lead to profound and lasting modifications in gene expression. Membrane receptors are activated by numerous chemical, biochemical and physical signals. They lead to immediate and often brief modifications in cell function. Recently acquired knowledge of the molecular structure of these receptors has led to striking advances in understanding their dysfunction and to the possibility of genetic diagnosis in patients and their families. These disorders manifest either by constitutive activation of the receptor, leading to endocrine tumoural afflictions, or, more often, by a functional anomaly of the receptor leading to resistance to endogenic and exogenic hormones.