scholarly journals Preferential association of the insulin-like growth factors I and II with metabolically inactive and active carrier-bound complexes in serum

1987 ◽  
Vol 241 (3) ◽  
pp. 745-750 ◽  
Author(s):  
H J Cornell ◽  
G Enberg ◽  
A C Herington
Keyword(s):  
Growth Factors ◽  
Formic Acid ◽  
Binding Protein ◽  
Gel Permeation Chromatography ◽  
Exchange Chromatography ◽  
Biologically Active ◽  
Igf I ◽  
Direct Contrast ◽  
First Time ◽  
Insulin Like Growth Factors

Ion-exchange chromatography of serum on DEAE-Sephadex A-50 using a stepwise NaCl gradient showed that complexes enriched with insulin-like growth factors I and II (IGF-I and IGF-II) could be preferentially eluted. A fraction eluted with 0.075 M-NaCl preferentially contained immunoreactive IGF-I with peak levels appearing in fractions of Mr approx. 110,000. The IGF-I-binding protein complex itself had low bioactivity as measured in a non-suppressible insulin-like (NSILA) bioassay. On conversion to free IGF-I by gel-permeation chromatography on Sephadex G-75 in 1% formic acid, however, the IGF-I did express its intrinsic NSILA bioactivity. In contrast, an IGF-II-enriched complex was eluted from the DEAE-Sephadex with 0.15 M-NaCl. Practically all of the recovered NSILA of the original serum was present in this fraction, in the Mr range 70,000-300,000 with a peak of 150,000. Chromatography on Sephadex G-75 in 1% formic acid separated this high-Mr NSILA into low-Mr (less than 15000) IGF-II and high-Mr acid-stable NSILA-P. The high-Mr IGF-II complex bound to concanavalin A-Sepharose, suggesting that it was a glycoprotein. The results confirm previous reports that a large portion of the NSILA of whole serum can be accounted for by a biologically active acid-dissociable complex. These data show for the first time that this active complex consists of an IGF-II-preferring binding protein. In direct contrast, the IGF-I-preferring complex does not express NSILA bioactivity until the IGF-I is liberated through acidification. The presence of a metabolically active IGF-II complex in serum raises questions as to its possible biological role in the adult.

Influence of insulin-like growth factor-binding protein-2 on plasma clearance and transfer of insulin-like growth factors-I and -II from plasma into mammary-derived lymph and milk of goats

1996 ◽  
Vol 150 (1) ◽  
pp. 121-127 ◽  
Author(s):  
C G Prosser ◽  
J Schwander
Keyword(s):  
Growth Factors ◽  
Growth Factor ◽  
Plasma Clearance ◽  
Binding Protein ◽  
Plasma Concentrations ◽  
Insulin Like Growth Factor ◽  
Factor Binding ◽  
Lactating Goats ◽  
Igf I ◽  
Insulin Like Growth Factors

Abstract Plasma clearance of insulin-like growth factors-I and -II (IGF-I and -II) and insulin-like growth factor-binding protein-2 (IGFBP-2) from lactating goats (n=4) was determined following a single intravenous injection of the corresponding 125I-labelled human protein. Transfer of these proteins out of the vascular space was monitored by their subsequent appearance in mammary-derived lymph and milk. Clearance of 125I-IGFBP-2 from circulation was 0·37 ± 0·06 ml/min/kg, which is markedly greater than that of 125I-IGF-I or -II (0·11 ± and 0·12 ± 0·01 ml/min/kg respectively). This was also reflected in longer elimination half-lives for IGF-I (353 ± 6 min) and -II (254 ± 8 min) compared with IGFBP-2 (110 ± 9 min). Three hours after injection of the 125I-labelled protein, the plasma:lymph ratio of trichloroacetic acid-precipitable radioactivity was 1·54 ±0·04, 3·3 ±0·6 and 4·1 ±0·4 for IGFBP-2, IGF-I and -II respectively. The form of 125I-IGFBP-2 in lymph was not different from that of plasma. Elevation of plasma concentrations of IGFBP-2 by its intravenous infusion significantly decreased plasma half-life of both IGF-I and -II (251 ± 8 and 198 ±7 min respectively). Although the amount and rate of transfer of IGF into mammary-derived lymph was decreased slightly by IGFBP-2, concentrations eventually obtained were not different from control. However, secretion of IGFs into milk was significantly reduced by IGFBP-2, particularly in the case of IGF-I. These results are consistent with the ability of all three compounds to cross the vascular endothelium intact and of IGFBP-2 to decrease the uptake of IGF by mammary epithelium and subsequent secretion into milk. IGFBP-2 may well have acted to target plasma IGF towards non-mammary tissues, thus explaining the more rapid plasma clearance of IGFs in the presence of elevated IGFBP-2. Journal of Endocrinology (1996) 150, 121–127

Serum levels of insulin-like growth factors (IGF-I and IGF-II) and their binding protein (IGFBP-3) are not elevated in pancreatic cancer

1997 ◽  
Vol 22 (2) ◽  
pp. 95-100
Author(s):  
James D. Evans ◽  
Margaret C. Eggo ◽  
Ian A. Donovan ◽  
Simon R. Bramhall ◽  
John P. Neoptolemos
Keyword(s):  
Pancreatic Cancer ◽  
Growth Factors ◽  
Binding Protein ◽  
Serum Levels ◽  
Igf I ◽  
Igfbp 3 ◽  
Insulin Like Growth Factors

Evaluation of the insulin-like growth factors (IGF) IGF-I and IGF binding protein 3 in patients at high risk for breast cancer

2011 ◽  
Vol 95 (8) ◽  
pp. 2753-2755 ◽  
Author(s):  
Angela F. Trinconi ◽  
José Roberto Filassi ◽  
José Maria Soares-Júnior ◽  
Edmund C. Baracat
Keyword(s):  
Breast Cancer ◽  
Growth Factors ◽  
High Risk ◽  
Binding Protein ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Insulin Like Growth Factors

scholarly journals Isolation of complexes formed between insulin-like growth factor-binding protein-3 and transferrin from the human serum

2012 ◽  
Vol 77 (5) ◽  
pp. 607-617 ◽  
Author(s):  
Goran Miljus ◽  
Miomir Petrovic ◽  
Olgica Nedic
Keyword(s):  
Growth Factors ◽  
Binding Protein ◽  
Biologically Active ◽  
Molecular Forms ◽  
Igf Binding Proteins ◽  
Igf Binding ◽  
The Relationship ◽  
Igfbp 3 ◽  
Insulin Like Growth Factors

Insulin-like growth factors (IGFs) play an important role in the regulation of cell growth, differentiation and metabolism. The amount of free, biologically active IGFs is regulated by the IGF-binding proteins (IGFBPs). IGFBP-3 is the most abundant binding protein and it is known to interact with other circulating proteins, including transferrin (Tf). In order to elucidate the possible role of IGF/IGFBP-3 in the iron metabolism, it is necessary to isolate IGFBP-3/Tf complexes. Several affinity-based techniques were employed. Results have shown that only double immunoprecipitation method with anti-Tf and anti-IGFBP-3 antibodies selectively separated complexes from other molecular forms, such as monomers, oligomers or fragments of IGFBP-3 and Tf. Isolated complexes can now be used to investigate the relationship between IGF/IGFBP-3 and iron, both in structural and metabolic t?rms.

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