Effect of protein deprivation on insulin-like growth factor-binding proteins in rats.
The effect of protein deprivation on plasma concentration of insulin-like growth factor-binding proteins (IGFBP) was studied in rats. A significant decrease in the concentration of IGFBP of molecular weight (mass) approximately 40 kDa was observed in protein-deprived rats. There was no prominent effect of protein deprivation on the concentration of IGFBP with molecular weights of about 30 kDa or 22-24 kDa. The binding capacity to plasma IGFBP of exogenously-added 125I-labelled insulin-like growth factor-1 (125I-IGF-1) was also studied. IGFBP of molecular weight about 30 and 22-24 kDa (the native form of this protein is presumed to be 29 kDa) in protein-deprived rat plasma bound more 125I-IGF-1 than those in protein-fed rat plasma. This suggested that these IGFBP in protein-deprived rat plasma are relatively unsaturated by endogenous IGF-1. The response of IGFBP to protein deprivation which was elucidated in the present investigations add further evidence to our previous assumption that IGFBP play an important role in protein nutrition.
Umezawa
T
T
Department of Agricultural Chemistry, Faculty of Agriculture, University of Tokyo, Japan.
Ohsawa
Y
Y
Miura
Y
Y
Kato
H
H
Noguchi
T
T
D000818:Animals; D015153:Blotting, Western; D002352:Carrier Proteins / Q000097:blood*; D004044:Dietary Proteins / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D005508:Food Deprivation / Q000502:physiology*; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000493:pharmacokinetics; D007457:Iodine Radioisotopes; D008297:Male; D008970:Molecular Weight; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D004044:Dietary Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D007457:Iodine Radioisotopes; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I