Insulin-like growth factors (IGFs) and IGF binding protein-3 display disulfide isomerase activity.
Biochem Biophys Res Commun
; 198(3): 1225-31, 1994 Feb 15.
Article
in En
| MEDLINE
| ID: mdl-7509599
ABSTRACT
Insulin-like growth factors (IGF-I and -II) bind with high affinity to IGF-binding proteins (IGFBPs). IGFBP-3 contains vicinal cysteines in sequence which is similar to the active sites in thioredoxin and protein disulfide isomerase. We tested if, in analogy with these redox enzymes, IGFBP-3 could catalyze the isomerization of intramolecular disulfide bridges in protein substrates. IGFBP-3 (30 microM) was able to reactivate reduced ribonuclease at a rate of 38% of that of thioredoxin. Also recombinant IGF-I induced the regeneration of ribonuclease activity. Thiol redox reactions are known to play a role in regulating conformational changes in the insulin receptor and possibly also in the IGF-I receptor. Therefore, the intrinsic isomerase activities of IGF-I may be important in the activation of its receptor. The observed effects of IGFBP-3 may help to elucidate the mechanism by which this binding protein can modulate the actions of IGF-I.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Insulin-Like Growth Factor I
/
Insulin-Like Growth Factor II
/
Carrier Proteins
/
Isomerases
Limits:
Animals
/
Humans
Language:
En
Journal:
Biochem Biophys Res Commun
Year:
1994
Document type:
Article
Affiliation country:
Netherlands