Family 2.A.4 - The Cation Diffusion Facilitator Family       

Family ID: 52615

The CDF family is a ubiquitous family, members of which are found in bacteria, archaea and eukaryotes. They transport heavy metals including cobalt, cadmium and zinc. All members of the CDF family possess six putative transmembrane spanners. These proteins exhibit an unusual degree of sequence divergence and size variation (300-750 residues). Eukaryotic proteins exhibit differences in cell localization and polarity. Thus, some catalyze heavy metal uptake while others catalyze efflux, and some are found in plasma membranes while others are in organellar membranes. Prokaryotic and eukaryotic proteins cluster separately. The mechanisms of energy coupling are not well understood, but these proteins are secondary carriers which utilize the pmf and therefore probably function by H+ antiport (for metal efflux) or H+ symport (for metal uptake).