scholarly journals Separation of the high affinity insulin-like growth factor I receptor from low affinity binding sites by affinity chromatography.

1987 ◽  
Vol 262 (34) ◽  
pp. 16461-16469 ◽  
Author(s):  
SE Tollefsen ◽  
K Thompson ◽  
DJ Petersen
Keyword(s):  
Growth Factor ◽  
Affinity Chromatography ◽  
Binding Sites ◽  
Affinity Binding ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
High Affinity ◽  
Growth Factor I

scholarly journals Evidence for separate receptors for insulin and insulin-like growth factor-I in choroid plexus of rat brain by quantitative autoradiography.

1990 ◽  
Vol 38 (9) ◽  
pp. 1289-1294 ◽  
Author(s):  
D A Davidson ◽  
N J Bohannon ◽  
E S Corp ◽  
D P Lattemann ◽  
S C Woods ◽  
...  
Keyword(s):  
Growth Factor ◽  
Choroid Plexus ◽  
Binding Sites ◽  
Porcine Insulin ◽  
Image Analysis System ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
High Affinity ◽  
Igf I ◽  
Growth Factor I

Binding of insulin and insulin-like growth factor-I (IGF-I) to the choroid plexus was quantitatively characterized using autoradiography and computer densitometry. Slide-mounted brain slices were incubated in 0.1 nM [125I]-insulin or [125I]-[Thr59]IGF-I. To determine specificity of the binding sites, the labeled peptides were mixed with unlabeled analogues. Autoradiography was done with LKB Ultrofilm and analyzed with a computer image analysis system and program for densitometry. Results showed that binding was time and temperature dependent and reversible. Binding of the iodinated insulin and IGF-I was inhibited by unlabeled peptides in a dose-dependent manner. The rank order of potency of these peptides in competing for the choroid plexus iodoinsulin binding sites was: chicken insulin greater than porcine insulin greater than desoctapeptide insulin greater than IGF-I. IGF-I was more potent than porcine insulin in competing for the choroid plexus iodolGF-I binding sites. Somatostatin was ineffective. Non-linear regression analysis revealed the presence of high- (Kd 1.3 +/- 0.2 nM) and low-affinity (Kd 36 +/- 1.4 nM) binding sites for insulin and a single high-affinity binding site (Kd 3.1 +/- 0.3 nM) for IGF-I in the choroid plexus. There were approximately 50 times more binding sites (Bmax) for IGF-I than for insulin high-affinity sites, whereas the number of low-affinity sites for insulin was about equal to the number of IGF-I high-affinity sites. The results of these binding studies with iodinated insulin and [Thr59]IGF-I support the conclusion that the rat choroid plexus has separate high-affinity receptors for insulin and IGF-I, and that the IGF-I receptors outnumber the insulin receptors.

Localization of binding sites for insulin-like growth factor-I (IGF-I) in the rat brain by quantitative autoradiography

1988 ◽  
Vol 444 (2) ◽  
pp. 205-213 ◽  
Author(s):  
Nancy J. Bohannon ◽  
Eric S. Corp ◽  
Barbara J. Wilcox ◽  
Dianne P. Figlewicz ◽  
Daniel M. Dorsa ◽  
...  
Keyword(s):  
Growth Factor ◽  
Rat Brain ◽  
Binding Sites ◽  
Quantitative Autoradiography ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

Insulin-like growth factor-I and its association with binding proteins in bovine milk

1989 ◽  
Vol 120 (1) ◽  
pp. 21-29 ◽  
Author(s):  
P. G. Campbell ◽  
C. R. Baumrucker
Keyword(s):  
Growth Factor ◽  
Binding Sites ◽  
Acid Treatment ◽  
Binding Protein ◽  
Bovine Milk ◽  
Immunoreactive Insulin ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I

ABSTRACT Immunoreactive insulin-like growth factor-I (IGF-I) in bovine milk was quantified. IGF-I was principally association with an ∼45 kDa binding protein. In addition, a small fraction of IGF-I occurred at a molecular weight approximately the same as that of unbound IGF-I. Available binding sites existed on the ∼45 kDa binding protein. Bound IGF-I was readily dissociated from binding protein by acid treatment. When IGF-I was estimated in milk obtained from primiparous and multiparous cows, multiparous cows had a higher concentration (40 μmol/l) at parturition than primiparous cows (19·2 μmol/l). By day 2 of lactation, IGF-I concentrations were 30 and 50% of initial estimates for multiparous and primiparous cows respectively. The final IGF-I concentration, on day 56 of lactation, was 4·5 μmol/l for combined parity groups. At parturition in multiparous cows, the mass of IGF-I was estimated at 183 and 157 μmol for blood and milk pools respectively. Milk, therefore, represents a substantial pool of IGF-I in the cow. The mechanism of the appearance of IGF-I in bovine milk is unknown. Journal of Endocrinology (1989) 120, 21–29

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