The structure of rat calbindin was originally solved by nuclear magnetic resonance and was one of the largest proteins then to be determined by this technique.

[3][4] There were differences observed between the nuclear magnetic resonance and crystal structure despite 98% sequence identity between the rat and human isoforms.

Calbindin is a vitamin D–responsive gene in many tissues, in particular the chick intestine, where it has a clear function in mediating calcium absorption.

Expression of S100G, like that of calbindin 1, is stimulated by the active vitamin D metabolite, calcitriol although the precise mechanisms are still controversial.

[10][11] Such proteins bound calcium in the micromolar range and were greatly reduced in vitamin D-deficient animals.

This article incorporates text from the United States National Library of Medicine, which is in the public domain.