RESUMO
This laboratory has advanced a model whereby retinol is transported around the body bound to retinol-binding protein (RBP), is transferred across the membrane of cells by a specific receptor/transporter, and is picked up from the membrane by an intracellular homolog, cellular retinol-binding protein (CRBP). This process involves a number of protein-protein interactions, and we hypothesized that conformational changes were an integral part of the retinol transfer mechanism. Previously we identified the potential interaction site on RBP for its membrane receptor. Here we confirm by the analysis of chimera containing a grafted CD loop from RBP that this is indeed the receptor interaction site and go on to demonstrate that the conformational changes that occur to this region on the apo to holo transition in RBP also take place in a chimera binding a quite different ligand, thus establishing the concept. We have also gone on to support the hypothesis that CRBP may also bind to a receptor in the membrane. Previous evidence has indicated that one such receptor might be lecithin:retinol acyltransferase, an enzyme that catalyzes retinol esterification. Here we provide the first evidence that the plasma membrane receptor for RBP could be the same as that for CRBP. This observation offers support for the intracellular phase of the uptake process for retinol, providing an efficient and highly unique mechanism in eukaryotic biology.
Assuntos
Receptores de Superfície Celular/metabolismo , Proteínas Celulares de Ligação ao Retinol/metabolismo , Proteínas de Ligação ao Retinol/química , Proteínas de Ligação ao Retinol/metabolismo , Animais , Apoproteínas/química , Apoproteínas/metabolismo , Sítios de Ligação , Humanos , Lipocalinas/genética , Lipocalinas/metabolismo , Camundongos , Modelos Biológicos , Modelos Moleculares , Conformação Proteica , Proteínas/genética , Proteínas/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Celulares de Ligação ao Retinol/químicaRESUMO
Statistical properties of eleven Y chromosome Short Tandem Repeat (STR) markers were analyzed (DYS391, DYS389I, DYS439, DYS389II, DYS438, DYS437, DYS19, DYS392, DYS393, DYS390 and DYS385) in a Greek population sample. The 200 subjects where distributed across Greece, from various Peripheries. 182 distinct haplotypes were found. To validate our results gene diversity has been calculated for the whole population, as well as for each locus individually. Genetic distance has been estimated between this population and Albanian, Egyptian, Italian and Turkish populations. The results indicate that all Y loci are useful for forensic sciences.