title: Purification and characterization of multiplication-stimulating activity. Insulin-like growth factors purified from rat-liver-cell-conditioned medium.
abstract: Multiplication-stimulating activity (MSA) refers to a family of insulin-like growth factors that have been purified from serum-free medium conditioned by a Buffalo rat liver cell line (BRL-3A). Using Dowex ion-exchange chromatography, gel chromatography on Sephadex G-75, and preparative disc acrylamide gel electrophoresis, several polypeptides with the full biological multiplication-stimulating activity have been isolated. One of these polypeptides, designated MSA II-1, previously has been used to study the relationship of the activity to the insulin-like growth factors (somatomedins) purified from human plasma. Polypeptide II-1 is a single chain polypeptide of molecular weight 8700. Glycine is the COOH-terminal amino acid. Edman degradation of carboxymethylated MSA II-1 did not reveal a free NH2-terminus. A polypeptide of lower molecular weight than MSA II-1 has also been purified. This polypeptide (MSA III-2) has been shown to be more potent than MSA II-1 in the rat-liver-membrane radioreceptor assay and in a competitive binding assay utilizing the rat-serum somatomedin-binding protein(s). The relationship of these various polypeptides has been investigated by gel filtration in guanidine hydrochloride and by acrylamide gel electrophoresis of the reduced and native polypeptides.
mesh_terms: D000596:Amino Acids / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D002352:Carrier Proteins / Q000097:blood; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002642:Chick Embryo; D003470:Culture Media; D004261:DNA Replication / Q000187:drug effects; D007328:Insulin / Q000302:isolation & purification* / Q000494:pharmacology; D018969:Insulin-Like Growth Factor Binding Proteins; D008099:Liver / Q000378:metabolism*; D008970:Molecular Weight; D010455:Peptides / Q000302:isolation & purification* / Q000494:pharmacology; D011869:Radioligand Assay; D051381:Rats; D013002:Somatomedins / Q000097:blood / Q000302:isolation & purification* / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D002352:Carrier Proteins; D003470:Culture Media; D007328:Insulin; D018969:Insulin-Like Growth Factor Binding Proteins; D010455:Peptides; D013002:Somatomedins