Isolation and NH2-terminal amino acid sequences of rat serum carrier proteins for insulin-like growth factors

Biochem Biophys Res Commun. 1988 Nov 15;156(3):1187-94. doi: 10.1016/s0006-291x(88)80758-7.

Abstract

Three N-glycosylated carrier proteins (CP) for insulin-like growth factors (apparent molecular weights 30-32, 42 and 45 kDa) were isolated from adult rat serum. They share the same amino terminus (up to amino acid 31) and are constituents of the growth hormone-dependent native 150-200 kDa IGF carrier complex. Residues 12-31 display 60 and 50% sequence homology, respectively, to residues 2-21 of fetal rat and to residues 4-22 of a human amniotic fluid IGF carrier protein. No homology exists with the type I or II IGF receptors. Adult rat serum also contains a fourth IGF CP (24 kDa) whose 9 NH2-terminal amino acids are identical to those of the fetal form. Our findings suggest that the three N-glycosylated components originate from the same IGF carrier protein (adult form) and that the 24 kDa protein is a separate (fetal) species.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Age Factors
  • Amino Acid Sequence
  • Amino Acids / analysis
  • Animals
  • Blotting, Western
  • Carrier Proteins / blood*
  • Chromatography, High Pressure Liquid
  • Molecular Sequence Data
  • Molecular Weight
  • Rats
  • Somatomedins / blood*

Substances

  • Amino Acids
  • Carrier Proteins
  • Somatomedins