Cobalamin transport

About: Cobalamin transport is a research topic. Over the lifetime, 72 publications have been published within this topic receiving 3088 citations.

Basal gnathostomes provide unique insights into the evolution of vitamin B12 binders.

Abstract: The uptake and transport of vitamin B12 (cobalamin; Cbl) in mammals involves a refined system with three evolutionarily related transporters: transcobalamin 1 (Tcn1), transcobalamin 2 (Tcn2), and the gastric intrinsic factor (Gif). Teleosts have a single documented binder with intermediate features to the human counterparts. Consequently, it has been proposed that the expansion of Cbl binders occurred after the separation of Actinopterygians. Here, we demonstrate that the diversification of this gene family took place earlier in gnathostome ancestry. Our data indicates the presence of single copy orthologs of the Sarcopterygii/Tetrapoda duplicates Tcn1 and Gif, and Tcn2, in Chondrichthyes. In addition, a highly divergent Cbl binder was found in the Elasmobranchii. We unveil a complex scenario forged by genome, tandem duplications and lineage-specific gene loss. Our findings suggest that from an ancestral transporter, exhibiting large spectrum and high affinity binding, highly specific Cbl transporters emerged through gene duplication and mutations at the binding pocket.

Clinical Features and Molecular Genetics of Autosomal Recessive Ataxia in the Turkish Population.

Abstract: Background: Autosomal recessive cerebellar ataxias (ARCAs) are a heterogeneous group of inherited neurodegenerative disorders The aim of this study was to present the clinical and genetic features of patients with ataxia complaints and those genetically diagnosed with ARCAs Materials and Methods: Thirty-one children with ARCA were retrospectively analyzed Results: Fourteen (452%) were boys and 17 (548%) were girls with the mean age at onset of symptoms of 4613 ± 2630 months (12–120 months) Of the 31 patients, 21 (677%) were from consanguineous marriages Eight patients had Friedreich’s ataxia, five had ataxia telangiectasia, three had l -2-hydroxyglutaric aciduria, three had Joubert syndrome, two had neuronal ceroid lipofuscinosis, two had megalencephalic leukoencephalopathy with subcortical cysts, two had ataxia with ocular motor oculomotor apraxia type 1, one had cytochrome c oxidase deficiency, one had autosomal recessive spastic ataxia of Charlevoix-Saguenay, one had Niemann-Pick type C, one had congenital disorders of glycosylation, one had adrenoleukodystrophy, and one had cobalamin transport disorder Conclusion: The prevalence of hereditary ataxia can vary among countries The consanguineous marriage is an important finding in these diseases These genetic tests will increase the number of ARCA patients diagnosed

The intrinsic factor receptor is present in the ileum of gastrectomized rats.

Abstract: The specific cobalamin transport proteins chemically resemble their receptors in cell membranes. They are therefore assumed to have developed as gene duplications of their receptors. Since the transport proteins have a great tendency to form oligomers, their attachment to their receptors seems to be analogous to the formation of an oligomer. However, the theoretical possibility exists that the receptor is the transport protein itself, internalized in the cell membrane. The ileum from gastrectomized rats is here shown to contain the intrinsic factor receptor, which disproves this hypothesis about the ileal receptor. Free intrinsic factor was found in extracts from control rat intestinal mucosa but not in that of gastrectomized animals.