Insulin: interaction with membrane receprots and relationship to cyclic purine nucleotides and cell growth.

摘要: Insulin action is discussed with emphasis on events that occur at the plasma membrane. A summary presented of previous studies which indicate insulin receptor fat and liver cells a large glycoprotein, partially buried in outer surface membrane, high (K-D approximately 10-10 M) specific affinity for insulin. The participation membrane phospholipids binding role sialic acid residues transmission signal are discussed. relation to its effects cyclic nucleotide levels explored. On one hand, (glucose transport) inhibited by compounds (cholera toxin, ACTH, glucagon L-norepinephrine) stimulate adenylate cyclase; conversely, both inhibits lipolytic these compounds, raises cellular GMP. An hypothesis whereby single cyclase species may be responsible formation either AMP or GMP, depending nature hormone stimulus. phosphorylation context experiments demonstrating inhibition ATP insulin-mediated glucose transport, association two proteins. ability modulate cultured act as growth factor stimulates DNA synthesis uptake alpha-aminoisobutyric human fibroblasts, also mediated epidermal factor. acts concentrations much higher than those obtained vivo, whereas thought physiological. sites equal 10-9 related growth, observed fibroblasts lectin-stimulated leukemic lymphocytes would not appreciably occupied physiological concentrations. implications such 'low affinity' other factors.