title: Insulin degradation in human erythrocyte: effects of cations.
abstract: Insulin degradation by human erythrocyte fractions was studied using the TCA-precipitation method. Hemolysate exhibited an insulin degrading activity higher than membranes. Triton X-100 treatment of membranes led to the appraisal of Triton-soluble degrading activity and of a more efficient Triton-not-soluble degrading activity. Monovalent cations (Na+, K+, Li+) did not modify the insulin degradation by any of the erythrocyte fractions. Divalent cations, Ca++ and Zn++ selectively enhanced insulin degradation by the membranous fractions, and Cu++ and Zn++ strongly inhibited insulin degradation by all the erythrocyte fractions. The results supported the hypothesis of the existence of at least two different degrading systems in human erythrocytes: soluble (cytosolic) Ca++ and Mg++ insensitive system(s) and membrane associated Ca++ and Mg++ sensitive system(s).
mesh_terms: D000328:Adult; D004910:Erythrocyte Membrane / Q000378:metabolism; D004912:Erythrocytes / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007328:Insulin / Q000097:blood*; D008297:Male; D008670:Metals / Q000494:pharmacology*
chemical_list: D007328:Insulin; D008670:Metals