Two site-specific radioimmunoassays which demonstrate the presence of proteolytically modified insulin-like growth factor-binding protein-3 in the circulation.
The presence of proteolytic activity in the circulation directed against insulin-like growth factor binding protein-3 (IGFBP-3) was originally described in pregnancy but has subsequently been described in a number of catabolic and other pathological conditions. However, detection of this proteolytically modified IGFBP-3 has been demonstrated, in most cases, following separation using SDS-PAGE and this has led to speculation that its occurrence may be an artefact of the harsh conditions employed. Using two site-specific antisera, one of which recognizes as its antigenic site a region of IGFBP-3 which is close to that of the IGF-binding domain, we have developed two radioimmunoassays which, when compared, can reveal alterations in the IGF-binding domain of IGFBP-3. The presence of IGFBP-3 modified by the circulating protease is denoted in this system by a divergence in the IGFBP-3 levels observed; this divergence has been shown to coincide with protease activity as determined by Western ligand blotting. The use of these assays has confirmed that the IGF-binding site of IGFBP-3 undergoes proteolytic modification in the circulation during a number of pathologies.
Cwyfan Hughes
S C
SC
Department of Chemical Endocrinology, St Bartholomew's Hospital, London, U.K.
Wass
J A
JA
Holly
J M
JM
D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D002352:Carrier Proteins / Q000032:analysis* / Q000378:metabolism; D005260:Female; D006130:Growth Disorders / Q000097:blood; D013006:Growth Hormone / Q000378:metabolism; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D010447:Peptide Hydrolases / Q000378:metabolism; D011184:Postoperative Period; D011247:Pregnancy; D011863:Radioimmunoassay / Q000379:methods; D013002:Somatomedins / Q000032:analysis* / Q000378:metabolism; D013312:Stress, Physiological / Q000097:blood
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D010447:Peptide Hydrolases