Defect in vitamin B12 release from lysosomes: newly described inborn error of vitamin B12 metabolism.
Cultured diploid fibroblasts from a patient with a previously undescribed inborn error of cobalamin metabolism accumulate unmetabolized, nonprotein-bound vitamin B12 in lysosomes. These cells are able to endocytose the transcobalamin II-B12 complex and to release B12 from transcobalamin II. The freed vitamin B12 is not released from lysosomes into the cytoplasm of the cell. This suggests that there is a specific lysosomal transport mechanism for vitamin B12 in the human.
D001692:Biological Transport; D002451:Cell Compartmentation; D002478:Cells, Cultured; D003593:Cytoplasm / Q000378:metabolism; D004705:Endocytosis; D005260:Female; D006801:Humans; D007223:Infant; D008247:Lysosomes / Q000378:metabolism*; D008661:Metabolism, Inborn Errors / Q000378:metabolism*; D014805:Vitamin B 12 / Q000378:metabolism*
D014805:Vitamin B 12