Multifaceted ammonia transporters

Abstract

ABSTRACT Ammonia homeostasis is essential for the normal functioning of macro-and microorganisms. The change in concentration of ammonia derivatives in intracellular and extracellular environments is a marker of nitrogen metabolism imbalance. Transport of these molecules is now known to occur by both simple diffusion and special membrane-associated transporters belonging to the Amt/MEP/Rh family. This protein family is subdivided into two subfamilies: the ammonium transporter (AMT)-methylammonium/ammonium permeases (MEP) and the rhesus (Rh) proteins. In this review, we systemize and generalize the long-established and some recent findings on the role of these proteins in nitrogen metabolism in general, and in the ammonia balance in particular. The similarities and differences of these systems in various living beings are discussed. The paper also focuses on the characteristics of several aspects of the classification and on the physiological importance of these proteins and their relationships to certain pathological processes. We also enumerate the prospects and unique challenges of research in this field of science. Deeper theoretical and practical research will provide a better understanding of the mechanisms underlying the structural-functional evolution of ammonia transport proteins, as well as the level of their involvement in the signaling pathways associated with the pathophysiology of nitrogen metabolism.