Insulin and IGF-1 binding in chick sclera.
Invest Ophthalmol Vis Sci
; 31(6): 1015-22, 1990 Jun.
Article
en En
| MEDLINE
| ID: mdl-2162332
The sclera of embryonic (days 10 and 14) and young adult (2-week posthatching chicks) contains distinct binding sites for insulin and for insulin-like growth factor-1 (IGF-1). Since there is a nearly 50% decrease in insulin and IGF-1 binding between embryonic day 10 and the 2nd week posthatching, it is clear that these sites are developmentally regulated. The affinity of each binding site for its ligand is stable across development. This suggests that the developmental decrease in binding is the result of a decrease in the number of binding sites. The insulin binding site in the sclera is specific for insulin since it has a high affinity for insulin and a lower affinity for IGF-1 (IC50 for unlabeled insulin = 0.4 nM; unlabeled IGF-1 = 5.0 nM). The embryonic chick sclera also contains two high-affinity IGF-1 binding sites. One of these sites exhibits poor binding specificity since it has an equal affinity for insulin and IGF-1. However, the specificity of this site increases in the young adult. The second IGF-1 binding site exhibits a more conventional specificity in that it has a higher affinity for IGF-1 than for insulin. The specificity of this binding site also improves in the young adult. The presence of insulin and IGF-1 receptor binding site subtypes is not correlated with structurally different receptor binding subunits since only a single population of binding subunits is observed (apparent molecular weight of 125 +/- 2.7 kD) in embryonic and adult sclera.(ABSTRACT TRUNCATED AT 250 WORDS)
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Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Esclerótica
/
Somatomedinas
/
Factor I del Crecimiento Similar a la Insulina
/
Insulina
Límite:
Animals
Idioma:
En
Revista:
Invest Ophthalmol Vis Sci
Año:
1990
Tipo del documento:
Article
Pais de publicación:
Estados Unidos