Binding of Insulin to a Muscle Cell Membrane Preparation

Insulin Receptors in the Liver: Specific Binding of [ 125 I]Insulin to the Plasma Membrane and Its Relation to Insulin Bioactivity

“…The binding of radioactively labeled insulin to tissues has been measured in many studies, including one reported recently (7) in which binding to the plasma membrane fraction from rat liver was studied, but uncertainties about the bioactivity of the iodinated molecules, the site of the binding, and proportion of "nonspecific" binding have limited the scope of the conclusions (8)(9)(10)(11)(12)(13)(14)(15). We developed a method for the preparation of monoiodoinsulin that is as active as uniodinated insulin in stimulating glucose oxidation in isolated fat cells (16,17).…”

Promotion of Myopathy by Polyunsaturated Fatty Acids of Cod Liver Oil

“…Tappel (30) has suggested that disruption of the lysosomal membrane may be a primary cause of dystrophy in vitamin E-deficient rabbits. In addition to the structural aspects, there is considerable evidence that both membrane sulfhydr-yl groups (31)(32)(33)(34)(35) and lipid unsaturated bonds (36-39) are related to permeability, although there is no direct evidence for a sulfhydrylolefin interaction. I t is not inconceivable that in chicks deficient in cystine and vitamin E, increased lysosomal membrane permeability may occur resulting in the excessive release of the lysosonlal enzymes into the cytoplasm.…”

Isolation of Skeletal Muscle Nuclei

“…Selection of a specific gravity-flotation method similar to that of Chauveau et al (7,8) was made because of our initial interest in the intracellular location of insulin (25). In these experiments, striated muscle pretreated with I131-1abeled hormone was fractionated into its subcellular components and the radioactivity of each component determined.…”

“…We elected not to use surface active detergents such as Cemulsol as described by Hubert et al (29) for the same reason, i.e., such agents would be expected to remove the outer nuclear membrane. Also, the use of an isolation technique employing citric acid was precluded because of the effectiveness of this agent in removing the outer nuclear membrane (30); and because our experiences with the effect of pH upon the insulin-sarcolemma complex suggested that an acid medium might reduce the amount of insulin bound to the nucleus (31). Prior to the fractionation procedure the muscles were handled in one of two ways.…”

“…Sprague-Dawley female rats weighing 225 to 250 gm are fasted for 24 hours, decapitated, and the intact femoral musculature is quickly removed and (25). After rinsing procedures, the tissue is fractionated for nuclei in the following manner.…”