This overview is intended to present recent information available on the
work done in
understanding the mode of entry of
cobalamin into and out of mammalian
cells. I have focused primarily on the uptake of
cobalamin bound to 3
proteins intrinsic factor,
transcobalamin II and R-
proteins. Even though the
nature of these
cobalamin binding proteins, and the receptors involved in the internalization of these
proteins is known, a total picture on the intracellular trafficking of
cobalamin and the
binding proteins is far from complete.