Regulation of transmembrane signalling elements: transcriptional, post-transcriptional and post-translational...

G-protein-mediated transmembrane signalling is a common motif in biology. The actions of a populous group of G-protein-linked receptors in hormone action, olfaction and vision in vertebrates are examples in which input signals are transferred from a receptor molecule (or photopigment) to an effector unit(s) via G-proteins. The expression and functional status of the receptors, G-proteins, and effectors that constitute these transmembrane signalling systems are regulated physiologically. Altering the abundance, function, or both of these elements provides the means for modulating transmembrane signalling and integration of information among separate pathways. Recent advances in the cell and molecular biology of transmembrane signalling elements provide insight as to the mechanisms by which regulation occurs. Transcriptional control is exemplified by glucocorticoid induction of beta-adrenergic receptor expression. Agonist-induced down-regulation of beta-adrenergic receptor mRNA via message destabilization best highlights post-transcriptional control. Examples of post-translational control of transmembrane signalling elements include protein phosphorylation, thioldisulphide exchange, and altered rates of protein degradation. Simultaneous analysis of physiological regulation at the levels of the gene, mRNA, and protein provide new opportunities for understanding how information processing extends from the plasma membrane to the genome.