Isolation and Partial Sequence Analysis of Rat Basic Somatomedin*

Abstract

Rat basic somatomedin (Sm) was prepared with an improved purification scheme from the pooled sera of Wistar Furth rats previously inoculated with cells from the pituitary tumor MStT/W15. Amicon hollow fiber diafiltration facilitated the processing of large batches of serum, eliminating the necessity of running smaller portions of material on gel filtration columns to achieve the same qualitative separation. The yield from this technique was excellent. Basic rat Sm was separated from a C3ades Arg component of complement by a narrow pH range isoelectric focusing step. Subsequent chromatography on carboxymethyl-cellulose and Sephadex resins was very efficient, providing a 100-fold purification, with a recovery of Sm activity of approximately 65%. The final product was judged to be pure by a variety of criteria. Structural analysis of this material has demonstrated that the amino-terminal sequences of rat basic Sm and human insulin-like growth factor I are strikingly similar, confirming the homology proposed earlier on the basis of receptor cross-reactivity.

Tissue and Serum Concentrations of Somatomedin-C/Insulin-Like Growth Factor I in Fetal Rats Made Growth Retarded by Uterine Artery Ligation

“…Rat homologues of human somatomedins (Sm-C/IGF I and IGF 11) have been purified. A peptide purified from adult rat serum bears marked homology to Sm-C/IGF 1 (22) and has been reported to be 30-40% as potent as Sm-C/IGF I in competing for binding to this antibody (23); MSA, the rat homologue of IGF 11 (24), crossreacts minimally with our antibody (1.2% for MSA 111-2 and 0.025% for MSA 11-1) (25). When this RIA is used to measure specimens from rats, it is likely to underestimate rat Sm-C/IGF I by 2.5 to 3.3-fold and to detect MSA only when it is present in very high concentrations.…”

Developmental Pattern of a Serum Binding Protein for Multiplication Stimulating Activity in the Rat

“…Recently, Marquardt et al (7) have reported that the amino acid sequence of one of the lower molecular weight species of MSA is identical to the primary structure of human IGF-II except for five amino acids and have proposed that MSA is rat IGF-II. Another rat IGF purified by Daughaday et al (8,9) shows amino acid sequence homology with human IGF-I. Using a radioimmunoassay for serum and that MSA levels gradually decline following birth to reach low concentrations by 25 d of extrauterine life (11).…”

Time Series Analysis of Plasma Insulin-like Growth Factor-I and Gonadal Steroids in Adolescent lapanese Macaques (Macaca fuscata).

“…Most of the previous results, however, were based on either the cross-sectional method or the short-term longitudinal method to GF-1 is a 70-amino-acid peptide and its production is known to be highly growth hormone (GH)-dependent [1][2][3][4] and to mediate biological actions of GH, including somatic growth [1,3]. The production and secretion of this peptide in the liver have been shown to be stimulated by GH in the human and rat [5,6].…”