Interaction of the vitamin D-binding protein (group-specific component) and its ligand 25-hydroxy-vitamin D3: binding differences of the various genetic types disclosed by isoelectric focusing.
The three common variants of the vitamin D binding protein, also known as group specific component (Gc), namely types 1S, 1F and 2, as well as some rare variants were studied by thin-layer polyacrylamide gel isoelectric focusing in a pH 4.5-5.4 carrier ampholyte generated pH gradient, additionally containing N-(2-acetamido)-2-aminoethanesulfonic acid (ACES). Prior to isoelectric focusing, whole serum or purified preparations of the vitamin D binding protein were incubated with 25-hydroxycholecalciferol at various ligand/protein ratios. Binding differences were found for the anodal and cathodal isoforms of Gc 1 variants and also for various allelic types. Isoforms with higher isoelectric points generally had a lower affinity for the ligand than the variants with lower isoelectric points.
Institut für Anthropologie und Humangenetik der Universität München, Federal Republic of Germany.
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Braun
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Brandhofer
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Cleve
D002112:Calcifediol / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007525:Isoelectric Focusing; D010641:Phenotype; D011485:Protein Binding; D014809:Vitamin D-Binding Protein / Q000235:genetics / Q000378:metabolism*
D014809:Vitamin D-Binding Protein; D002112:Calcifediol