Human Cluster of Differentiation 320 (CD320) Protein

Background

CD320, also known as the CD320 molecule or the transcobalamin receptor, is a cell surface protein involved in the transport and cellular uptake of vitamin B12 (cobalamin). It plays a pivotal role in maintaining cellular cobalamin levels, essential for critical cellular functions such as DNA synthesis, red blood cell formation, and neurological health. CD320 facilitates the binding and endocytosis of transcobalamin (TC)-bound vitamin B12 into cells, thus supporting cellular metabolism and growth. It is expressed in various tissues, with heightened expression in tissues requiring high levels of cobalamin, such as the liver, kidneys, and certain regions of the brain. This protein is particularly important in hematopoiesis and nervous system function due to its role in maintaining adequate levels of cobalamin for the function of enzymes involved in methylation and mitochondrial DNA synthesis. CD320 is also gaining attention in immunology, as it has been identified on B cells and other antigen-presenting cells (APCs), suggesting a broader immunomodulatory role. Mutations or deficiencies in CD320-mediated cobalamin uptake are associated with metabolic and hematological disorders, highlighting its essential function in human health.