Characterization of insulin-like growth factor binding protein-3 in chronic renal failure serum.
IGF-binding protein-3 (IGFBP-3), usually found as glycosylated 41- and 38-kD forms, is the major serum IGFBP during extrauterine life. In normal serum IGFBP-3 binds one IGF peptide and one acid-labile (alpha) subunit in a high-molecular-weight (MW) complex of 150 kD. By RIA, an excess of IGFBP-3 is present in chronic renal failure (CRF) serum, where it reportedly accumulates at low MW (25-55 kD) rather than as part of the 150-kD complex. To further evaluate IGFBP-3 forms in CRF, sera were obtained from seven healthy adolescents and seven adolescents with CRF. By RIA, IGFBP-3 levels were higher in CRF than normal sera (15.4 +/- 2.2 versus 10.1 +/- 2.1 micrograms/mL). High-MW (150-kD) fractions of CRF and normal sera, obtained by neutral size-exclusion chromatography, had equal amounts of IGFBP-3 by RIA. However, a second RIA peak of IGFBP-3, present in low-MW (35-kD) fractions of CRF but not normal sera, could account for the higher IGFBP-3 levels of CRF serum. [125I]IGF ligand blots of whole serum and serum fractions, either with or without prior precipitation by IGFBP-3 antiserum, found levels of 41- and 38-kD IGFBP-3 forms to be similar between CRF and normal whole sera and located these forms in the high-MW (150-kD) fractions of CRF and normal sera.(ABSTRACT TRUNCATED AT 250 WORDS)
Powell
D R
DR
Department of Pediatrics, Baylor College of Medicine, Houston, Texas 77030.
Liu
F
F
Baker
B
B
Lee
P D
PD
Belsha
C W
CW
Brewer
E D
ED
Hintz
R L
RL
D000293:Adolescent; D002352:Carrier Proteins / Q000097:blood* / Q000737:chemistry / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D002850:Chromatography, Gel; D003432:Cross-Linking Reagents; D006031:Glycosylation; D006130:Growth Disorders / Q000209:etiology; D006801:Humans; D007223:Infant; D018969:Insulin-Like Growth Factor Binding Proteins; D007676:Kidney Failure, Chronic / Q000097:blood* / Q000150:complications; D008970:Molecular Weight; D011233:Precipitin Tests; D011863:Radioimmunoassay; D011869:Radioligand Assay; D013002:Somatomedins / Q000378:metabolism*
D002352:Carrier Proteins; D003432:Cross-Linking Reagents; D018969:Insulin-Like Growth Factor Binding Proteins; D013002:Somatomedins