Résumé
The evolution of multicellular organisms has been conditioned by the capacity of their cells to communicate in order to coordinate their cell division, their cellular differentiation, their embryonic development as well as their different physiological functions. The messages used for cellular communication are hormones, neurotransmitters, growth and differentiation factors, cytokines, chemokines. The receptors for these messages as well as receptors for messages of the environment such as odors, light, tasteful molecules are, in most cases, membrane-bound molecules with steroid and thyroid hormone receptors as the important exception. During the last 10 years, purification and cloning of most of these receptors have revealed that they belong to a small number of protein families characterized by their structure and their functions. These families include: 1) receptor which are channels, such as the nicotinic receptor; 2) receptors which are enzymes such as the tyrosine kinases (insulin, EGF, PDGF receptors), the guanylate cyclase receptors (atrial natriuretic factor receptors), or serine/threonine kinases (TGF-β receptors); 3) receptors for cytokines (Il2,Il3,GH, prolactin, interferon) which activate separate tyrosine kinases (Jak and fyn kinases); 4) GTP binding protein (G proteins) coupled receptors (GPCRs).