Is the calcium transporter a potential candidate for heme transport?

Heme is of significant importance in iron nutrition and in systemic iron metabolism. The crux of the matter is that while much is known about non-heme metabolism, the vectorial import of exogenous porphyrin macromolecules into the enterocyte and possibly into blood circulation is still speculative. The inhibitory effect of calcium on heme iron absorption has been previously reported in the literature. This paper postulates that the gastrointestinal Ca transporter, TRPV6, might be a putative transporter of heme and might account for reduced heme absorption in the presence of Ca. The hypothesis needs to be investigated in vitro and in vivo with targeted TRPV6 deletion models to explore the nature of the competitive inhibition of heme uptake by Ca. Studies are required to characterize fully this function in the gut and in systemic metabolism. If the hypothesis is proven, modulators of TRPV6 expression could have clinical implications in the management of heme-induced disorders.