title: Insulin binding and response in erythroblastic leukemic cells.
abstract: Mammalian erythrocytes have been shown to bind, but not to respond to, physiologic doses of insulin. Insulin binding was studied in normal rat erythrocytes and erythroblastic leukemic (EBL) cells by standard 125I-insulin competitive binding assays. EBL cells exhibited marked insulin degradation, which was time, temperature, and concentration dependent and was mediated by both cell-bound and soluble enzymes. Bacitracin or bovine serum albumin was used to inhibit such degradation in a dose-dependent fashion to allow meaningful data analysis. Insulin binding studies showed a greater than 10-fold increase of specific binding to EBL cells compared with erythrocytes. Scatchard analysis was consistent with increases predominantly in the number of receptors on EBL cells. Concordant with increased insulin binding, EBL cells demonstrated increased transport of alpha-aminolsobutyric acid and increased incorporation of uridine into ribonucleic acid in response to physiologic doses of insulin (100 microunits/ml). It can be concluded that EBL cells may serve as useful models of erythroblasts to explore the relationships between insulin binding, response, and cell maturation.
mesh_terms: D000621:Aminoisobutyric Acids / Q000097:blood; D000818:Animals; D001667:Binding, Competitive; D001692:Biological Transport; D004912:Erythrocytes / Q000378:metabolism*; D007328:Insulin / Q000097:blood*; D007700:Kinetics; D007942:Leukemia, Experimental / Q000097:blood*; D012313:RNA / Q000096:biosynthesis; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism*; D013696:Temperature; D014529:Uridine / Q000378:metabolism
chemical_list: D000621:Aminoisobutyric Acids; D007328:Insulin; D012313:RNA; D011972:Receptor, Insulin; D014529:Uridine