Malbon C C, Hadcock J R, Rapiejko P J, Ros M, Wang H Y, Watkins D C
Department of Pharmacology, State University of New York, Stony Brook 11794.
Biochem Soc Symp. 1990;56:155-64.
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.
G蛋白介导的跨膜信号传导是生物学中的一个常见模式。在脊椎动物的激素作用、嗅觉和视觉中，大量G蛋白偶联受体的作用就是例子，其中输入信号通过G蛋白从受体分子（或视色素）传递到效应器单元。构成这些跨膜信号系统的受体、G蛋白和效应器的表达及功能状态受到生理调节。改变这些元件的丰度、功能或两者，为调节跨膜信号传导及在不同途径间整合信息提供了手段。跨膜信号元件的细胞和分子生物学的最新进展，为了解调节发生的机制提供了线索。糖皮质激素诱导β-肾上腺素能受体表达就是转录控制的一个例子。激动剂通过信息不稳定导致β-肾上腺素能受体mRNA下调，这最能体现转录后控制。跨膜信号元件翻译后控制的例子包括蛋白质磷酸化、硫醇-二硫键交换以及蛋白质降解速率的改变。在基因、mRNA和蛋白质水平同时分析生理调节，为理解信息处理如何从质膜延伸到基因组提供了新机会。
