Isolation and NH2-terminal amino acid sequences of rat serum carrier proteins for insulin-like growth factors.
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.
Zapf
J
J
Department of Medicine, University Hospital, Zürich, Switzerland.
Born
W
W
Chang
J Y
JY
James
P
P
Froesch
E R
ER
Fischer
J A
JA
D000367:Age Factors; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood*; D002851:Chromatography, High Pressure Liquid; D008969:Molecular Sequence Data; D008970:Molecular Weight; D051381:Rats; D013002:Somatomedins / Q000097:blood*
D000596:Amino Acids; D002352:Carrier Proteins; D013002:Somatomedins