Kinetic analysis of transcellular passage of the cobalamin-transcobalamin complex in Caco-2 monolayers
| Autor: | Christian B. Juul, Sergey N. Fedosov, Christian W. Heegaard, Ebba Nexo |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2019 |
| Předmět: |
Vitamin B 12/metabolism
Receptors Cell Surface Biology Ligands Cobalamin 03 medical and health sciences chemistry.chemical_compound 0302 clinical medicine Transcobalamin Cell surface receptor Animals Humans Transcellular Cobalt Radioisotopes Receptor Receptors Cell Surface/metabolism Molecular Biology 030304 developmental biology Transcobalamins 0303 health sciences Transcobalamins/metabolism Biological Transport Articles Cell Biology Transport protein Dissociation constant Vitamin B 12 Kinetics chemistry Transcytosis Membrane Trafficking 030220 oncology & carcinogenesis Biophysics Cattle Caco-2 Cells |
| Zdroj: | Juul, C B, Fedosov, S, Nexø, E & Heegaard, C W 2019, ' Kinetic analysis of transcellular passage of the cobalamin-transcobalamin complex in Caco-2 monolayers ', Molecular Biology of the Cell, vol. 30, no. 4, pp. 467-477 . https://doi.org/10.1091/mbc.E18-09-0571 Molecular Biology of the Cell |
| DOI: | 10.1091/mbc.E18-09-0571 |
| Popis: | We suggest a novel kinetic approach to quantifying receptor–ligand interactions via the cellular transport and/or accumulation of the ligand. The system of cobalamin (Cbl, vitamin B12) transport was used as a model, because Cbl is an obligatory cofactor, taken up by animal cells with the help of a transport protein and a membrane receptor. Bovine transcobalamin (bTC) stimulated the cellular accumulation and transcytosis of radioactive [57Co]Cbl in polarized monolayers of Caco-2 cells. The bovine protein was much more efficient than human TC. The transport was inhibited in a dose-dependent manner by the unlabeled bTC-Cbl complex, the ligand-free bTC, and the receptor-associated protein (RAP). This inhibition pattern implied the presence of a megalin-like receptor. Quantitative assessment of kinetic records by the suggested method revealed the apparent concentration of receptors in vitro (≈15 nM), as well as the dissociation constants of bTC–Cbl ( Kd= 13 nM) and RAP ( Kd= 1.3 nM). The data were used to estimate the effective luminal concentrations of TC-specific receptors in kidneys (3.8 µM) and intestine (50 nM), the tissues resembling polarized Caco-2 cells. |
| Databáze: | OpenAIRE |
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