Vitamin D Research Today is a free monthly online journal that collates and summarizes the latest research about Vitamin D, including details on sources, melanin, benefits, deficiency, supplements, calcium absorption. | ||||||||
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Cross-talk among structural domains of human DBP upon binding 25-hydroxyvitamin D.Ray A, Swamy N, Ray R Bioorganic Chemistry & Structural Biology, Department of Medicine, Boston University School of Medicine, 85 East Newton Street, Boston, MA 02118, USA. Serum vitamin D-binding protein (DBP) is structurally very similar to serum albumin (ALB); both have three distinct structural domains and high cysteine-content. Yet, functionally they are very different. DBP possesses high affinity for vitamin D metabolites and G-actin, but ALB does not. It has been suggested that there may be cross-talk among the domains so that binding of one ligand may influence the binding of others. In this study we have employed 2-p-toluidinyl-6-sulfonate (TNS), a reporter molecule that fluoresces upon binding to hydrophobic pockets of DBP. We observed that recombinant domain III possesses strong binding for TNS, which is not influenced by 25-hydroxyvitamin D(3) (25-OH-D(3)), yet TNS fluorescence of the whole protein is quenched by 25-OH-D(3). These results provide a direct evidence of cross-talk among the structural domains of DBP. Published 17 December 2007 in Biochem Biophys Res Commun, 365(4): 746-50.
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