Advances in the understanding of cobalamin assimilation and metabolism

Br J Haematol. 2010 Jan;148(2):195-204. doi: 10.1111/j.1365-2141.2009.07937.x. Epub 2009 Oct 12.


The haematological and neurological consequences of cobalamin deficiency define the essential role of this vitamin in key metabolic reactions. The identification of cubilin-amnionless as the receptors for intestinal absorption of intrinsic factor-bound cobalamin and the plasma membrane receptor for cellular uptake of transcobalamin bound cobalamin have provided a clearer understanding of the absorption and cellular uptake of this vitamin. As the genes involved in the intracellular processing of cobalamins and genetic defects of these pathways are identified, the metabolic disposition of cobalamins and the proteins involved are being recognized. The synthesis of methylcobalamin and 5'-deoxyadenosylcobalamin, their utilization in conjunction with methionine synthase and methylmalonylCoA mutase, respectively, and the metabolic consequences of defects in these pathways could provide insights into the clinical presentation of cobalamin deficiency.

Publication types

  • Research Support, N.I.H., Extramural
  • Review

MeSH terms

  • Biological Transport, Active
  • Humans
  • Intestinal Absorption / physiology*
  • Intrinsic Factor / genetics
  • Intrinsic Factor / metabolism
  • Metabolism, Inborn Errors / genetics
  • Metabolism, Inborn Errors / physiopathology
  • Receptors, Cell Surface
  • Transcobalamins / genetics
  • Transcobalamins / metabolism
  • Vitamin B 12 / metabolism*
  • Vitamin B 12 Deficiency / etiology*
  • Vitamin B 12 Deficiency / genetics


  • Receptors, Cell Surface
  • Transcobalamins
  • intrinsic factor-cobalamin receptor
  • Intrinsic Factor
  • Vitamin B 12