Transporter Biology and Physiology - Michael F. Romero

Divalent Cation Transporters

DCT1/NRAMP2
Several years ago, we collaborated with Drs. Matthias Hediger and Hiromi Gunshin to expression clone an inducible iron uptake protein cDNA from the rat small intestine. The resulting cDNA was found to be a general divalent cation transporter or DCT1. Sequencing of the resulting cDNA revealed that DCT1 was in fact the rat homolog of NRAMP2, a macrophage resistance factor of previously unknown function.

Functionally, DCT1 is an electrogenic, divalent transition-metal / H+ cotransporter. Subsequent studies have focused on the molecular determinants of DCT1 function, especially associated conductances.

Recently in collaboration with Dr. Michael Maguire's lab, we are characterizing bacterial NRAMP proteins as expressed in Xenopus oocytes.

Zinc transporters, ZnT1
ZnT1 is the founding member of a family of putative Zn2+ transporters. In collaboration with Dr. Robert Colvin, we are expressing ZnT1 in Xenopus oocytes. Our goal is to understand the mechanism and mode of Zn2+ transport.

Ca2+ and Mg2+ transporters
Ca2+ and Mg2+ transport is vital to life as well as central to the physiology of several organ systems. Many Ca2+ transporters and channels have been reported in the literature. Though Mg2+ transporters have been functional characterized in several mammalian cell types, especially the kidney, liver, and heart, a true mammalian Mg2+ transporter or channel is not forth coming.

In collaboration with Dr. Michael Maguire's lab, we are developing strategies to clone and characterize bacterial and mammalian Mg2+ transporters.