Molecular mechanisms of insulin signal transduction
Hormones and other extracellular stimuli that act via cell-surface receptors require a system or mechanism to translate their binding to the receptor into a cellular response. These mechanisms are generally referred to as transmembrane signalling systems, and usually involve the generation of small molecules within the cell that lead to the various cellular changes. These small molecules are referred to as second messengers. The basic components of a transmembrane signalling system are therefore a receptor coupled to the generation of a second messenger. There are however a few intervening steps as follows. The vast majority of receptors studied to date appear to be coupled to guanine-nucleotide regulatory proteins (G proteins). These in turn are coupled to the so-called effector enzyme, which is the one responsible for the generation of a second messenger. Once the messenger is generated it then acts upon its target enzymes, thereby causing the cellular responses. The terminology used in this area is usually similar to that of electronics and thus the coupling regulatory proteins are occasionally referred to as the ‘transducers’ and the effector enzyme as the ‘amplifier’.
KeywordsInsulin Action cAMP Level Phosphatidic Acid Pertussis Toxin Inositol Phosphate
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