In humans, the RhAG, RhBG, and RhCG Rhesus proteins constitute solute carrier family 42[2] whilst RhD and RhCE form the Rh blood group system.

[15][16][17] If NH4+ is transported, K+ possibly serves as a counter ion in an antiport process with K+, and that one histidine removes a proton off of NH4+ to yield NH3.

[15] The generalized transport reaction catalyzed by members of the Amt family are suggested to be: The X-ray structures have revealed that the pore of the Amt and Rh proteins is characterized by a hydrophobic portion about 12 Å long, in which electronic density was observed in the crystallographic study of AmtB from Escherichia coli.

This electronic density was initially only observed when crystals were grown in the presence of ammonium, and was thus attributed to ammonia molecules.

The possible presence of water molecules in the pore lumen calls for a reassessment of the notion that Amt/Rh proteins work as plain NH3 channels.

This deactivation is achieved by deuridylylation of the GlnK protein which then binds to the cytoplasmic face of AmtB and inserts a loop into the ammonia conducting pore.