[Molecular defects in plasma membrane hormone receptors]

The biological effects of hormones are mediated by plasma membrane receptors which transmit extracellular signals to the cytoplasm and nucleus. Mutations in plasma membrane receptors can affect normal signal transduction with loss-of-function mutations leading to hormone resistance and gain-of-function mutations leading to constitutive activation of signaling pathways. The loss-of-function mutations leading to familial hormone resistance disorders are germline in origin whereas the gain-of-function mutations leading to constitutively active receptors are somatic. G-protein coupled receptors (GPCR) comprise a large superfamily of proteins characterized by seven transmembrane-spanning segments and interaction with GTP-binding(G) proteins. Mutations in GPCRs have been associated with dwarfism, congenital hyperthyroidism or hypothyroidism, nephrogenic diabetes insipidus, obesity, resistance to TSH, LH, FSH and ACTH, Jansen's metaphyseal and Blomstrand's chondrodysplasia, autosomal dominant hypoparathyroidism, and neonatal severe hyperparathyroidism. Mutations in other families of receptors which are characterized into one spanning-transmembrane receptor can result in resistance to insulin, GH, leptin and AMH. This review summarizes the molecular defects in plasma membrane hormone receptors in a large number of clinical disorders.