Different Transport Mechanisms in Plant and Human AMT/Rh-type Ammonium Transporters

Transport Mechanisms in Plant and Human AMT/Rh-type Ammonium Transporters

Evolution of Electrogenic Ammonium Transporters (AMTs)

The ammonium transporter gene family consists of three main clades, AMT, MEP, and Rh. The evolutionary history of the AMT/MEP/Rh gene family is characterized by multiple horizontal gene transfer events, gene family expansion and contraction, and gene loss; thus the gene tree for this family of transporters is unlike the organismal tree. The genomes of angiosperms contain genes for both electrog...

Regulation of NH4+ transport by essential cross talk between AMT monomers through the carboxyl tails.

Ammonium transport across plant plasma membranes is facilitated by AMT/Rh-type ammonium transporters (AMTs), which also have homologs in most organisms. In the roots of the plant Arabidopsis (Arabidopsis thaliana), AMTs have been identified that function directly in the high-affinity NH4+ acquisition from soil. Here, we show that AtAMT1;2 has a distinct role, as it is located in the plasma memb...

Distinct transport mechanisms in yeast ammonium transport/sensor proteins of the Mep/Amt/Rh family and impact on filamentation.

Ammonium transport proteins of the Mep/Amt/Rh family include microbial and plant Mep/Amt members, crucial for ammonium scavenging, and animal Rhesus factors likely involved in ammonium disposal. Recent structural information on two bacterial Mep/Amt proteins has revealed the presence, in the hydrophobic conducting pore, of a pair of preserved histidines proposed to play an important role in sub...

Regulatory levels for the transport of ammonium in plant roots.

Ammonium is an attractive nitrogen form for root uptake due to its permanent availability and the reduced state of the nitrogen. On the other hand, ammonium fluxes are difficult to control because ammonium represents an equilibrium between NH4+ and NH3, which are two N forms with different membrane permeabilities. There is increasing evidence that AMT-type ammonium transporters represent the ma...