Abstract
Involvement of Ca^<2+>ion in the formation of macromolecular complex of vitamin B_<12>, intrinsic factor and receptor prepared from rat ileum mucosa was investigated by using ^<45>Ca ion and ^<57>Co-B_<12>. Filtration of the complex through Biogel column revealed that the eluted position of ^<57>Co coincided with that of ^<45>Ca. By the treatment of this complex with EDTA, the position of ^<45>Ca in the eluent shifted to that of free ^<45>Ca ion. These results indicate that ^<45>Ca is bound to this complex and plays an important role in the formation of B_<12>-intrinsic factor-receptor complex.
