title: Characterization of a somatomedin (insulin-like growth factor) synthesized by fetal rat liver organ cultures.
abstract: Explants of 19- to 20-day fetal rat liver synthesize polypeptides biochemically and immunologically related to the well characterized somatomedin (insulin-like growth factor) BRL-MSA, multiplication-stimulating activity. Fetal MSA was purified from media conditioned by fetal liver explants by chromatography on Sephadex G-75 under acid conditions. Partially purified fetal MSA: 1) inhibited the binding of BRL-MSA to the MSA receptor of rat liver plasma membranes, to somatomedin-binding proteins from rat serum, and to rabbit anti-BRL-MSA serum; 2) had a molecular weight of 4,500 to 12,500 determined by polyacrylamide gel electrophoresis in sodium dodecyl sulfate; 3) stimulated the incorporation of [3H]thymidine into the DNA of chick embryo fibroblasts and induced cell multiplication; 4) stimulated glucose oxidation in rat adipocytes and weakly inhibited the binding of insulin to the insulin receptors of IM-9 lymphocytes; and 5) stimulated sulfate uptake in costal cartilage from hypophysectomized rats. These activities were associated with the same molecular species in fetal MSA preparations following disc acrylamide electrophoresis and co-migrated with active BRL-MSA peptides.
mesh_terms: D000818:Animals; D001681:Biological Assay; D002642:Chick Embryo; D003513:Cycloheximide / Q000494:pharmacology; D005333:Fetus; D007328:Insulin; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D009924:Organ Culture Techniques; D011863:Radioimmunoassay; D051381:Rats; D013002:Somatomedins / Q000096:biosynthesis* / Q000302:isolation & purification
chemical_list: D007328:Insulin; D013002:Somatomedins; D003513:Cycloheximide