Nedic O, Filimonovic D, Mikovic Z, Masnikosa R. Influence of placental mannose/n-acetyl glucosamine-binding proteins on the interaction of insulin and insulin-like growth factors with their receptors.
BIOCHEMISTRY. BIOKHIMIIA 2011;
76:1003-1008. [PMID:
22082268 DOI:
10.1134/s0006297911090033]
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Abstract
Placenta is a source of carbohydrate-binding proteins that function as molecular scavengers, but they could also be involved in interactions that assist in metabolic control. Mannose/N-acetyl-glucosamine (Man/GlcNAc)-binding proteins from placenta were isolated and their reactivity towards placental insulin and insulin-like growth factor receptors (IR and IGF-Rs) was analyzed. The lectins reduced the binding of insulin and IGF-I in a dose-dependent manner, while almost no effect was observed on the binding of IGF-II. The shape of the inhibition curves changed, suggesting altered binding specificity. The presence of sugar could not reverse completely the effect of the lectins, implicating both lectin-sugar and protein-protein conformational recognition. Since biological molecules in our experimental system were those that are in close relation in vivo, placental Man/GlcNAc-specific lectins may be regarded as potential allosteric modulators of ligand-receptor interactions in a system of homologous ligands, selectively affecting only binding to tyrosine kinase type receptors (IR and IGF-1R).
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