Na+/H+ antiporter 1 | |||||||||||
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Identifiers | |||||||||||
Symbol | Na_H_antiport_1 | ||||||||||
Pfam | PF06965 | ||||||||||
InterPro | IPR004670 | ||||||||||
TCDB | 2.A.36 | ||||||||||
OPM superfamily | 106 | ||||||||||
OPM protein | 1zcd | ||||||||||
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Na+/H+ antiporter A (NhaA) family (TC# 2.A.33) contains a number of bacterial sodium-proton antiporter (SPAP) proteins. These are integral membrane proteins that catalyse the exchange of H+ for Na+ in a manner that is highly pH dependent. Homologues have been sequenced from a number of bacteria and archaea. Prokaryotes possess multiple paralogues. A representative list of the proteins that belong to the NhaA family can be found in the Transporter Classification Database.
Proteins of the NhaA family are of 300-700 amino acyl residues in length. NhaA of E. coli is a homeodimer, each subunit consisting of a bundle of 12 tilted transmembrane α-helices (TMSs). [1] [2] [3] [4] [5]
Molecular dynamics simulations of NhaA enabled proposal of an atomically detailed model of antiporter function. [6] Three conserved aspartate residues are key to this proposed mechanism: Asp164 (D164) is the Na+-binding site, D163 controls the alternating accessibility of this binding site to the cytoplasm or periplasm, and D133 is crucial for pH regulation. [6] [7] [8]
Na+-H+ antiporters are integral membrane proteins that exchange Na+ for H+ across the cytoplasmic membrane and many intracellular membranes. They are essential for Na+, pH, and volume homeostasis, which are processes crucial for cell viability. [8] [9] The E. coli protein probably functions in the regulation of the internal pH when the external pH is alkaline, and the protein effectively functions as a pH sensor. [7] It also uses the H+ gradient to expel Na+ from the cell. Its activity is highly pH dependent. [3] [10]
The generalized transport reaction catalyzed by NhaA is: [6] [11]
Na+ (in) + 2H+ (out) ⇌ Na+ (out) + 2H+ (in).
Respiratory complex I, EC 7.1.1.2 is the first large protein complex of the respiratory chains of many organisms from bacteria to humans. It catalyzes the transfer of electrons from NADH to coenzyme Q10 (CoQ10) and translocates protons across the inner mitochondrial membrane in eukaryotes or the plasma membrane of bacteria.
An antiporter is an integral membrane protein that uses secondary active transport to move two or more molecules in opposite directions across a phospholipid membrane. It is a type of cotransporter, which means that uses the energetically favorable movement of one molecule down its electrochemical gradient to power the energetically unfavorable movement of another molecule up its electrochemical gradient. This is in contrast to symporters, which are another type of cotransporter that moves two or more ions in the same direction, and primary active transport, which is directly powered by ATP.
An efflux pump is an active transporter in cells that moves out unwanted material. Efflux pumps are an important component in bacteria in their ability to remove antibiotics. The efflux could also be the movement of heavy metals, organic pollutants, plant-produced compounds, quorum sensing signals, bacterial metabolites and neurotransmitters. All microorganisms, with a few exceptions, have highly conserved DNA sequences in their genome that encode efflux pumps. Efflux pumps actively move substances out of a microorganism, in a process known as active efflux, which is a vital part of xenobiotic metabolism. This active efflux mechanism is responsible for various types of resistance to bacterial pathogens within bacterial species - the most concerning being antibiotic resistance because microorganisms can have adapted efflux pumps to divert toxins out of the cytoplasm and into extracellular media.
The sodium–hydrogen antiporter or sodium–proton exchanger (Na+/H+ exchanger or NHX) is a membrane protein that transports Na+ into the cell, and H+ out of the cell (antiport).
The major facilitator superfamily (MFS) is a superfamily of membrane transport proteins that facilitate movement of small solutes across cell membranes in response to chemiosmotic gradients.
Multidrug and toxin extrusion protein 1 (MATE1), also known as solute carrier family 47 member 1, is a protein that in humans is encoded by the SLC47A1 gene. SLC47A1 belongs to the MATE family of transporters that are found in bacteria, archaea and eukaryotes.
Multidrug and toxin extrusion protein 2 is a protein which in humans is encoded by the SLC47A2 gene.
Multi-antimicrobial extrusion protein (MATE) also known as multidrug and toxin extrusion or multidrug and toxic compound extrusion is a family of proteins which function as drug/sodium or proton antiporters.
Members of the Solute:Sodium Symporter (SSS) Family (TC# 2.A.21) catalyze solute:Na+ symport. The SSS family is within the APC Superfamily. The solutes transported may be sugars, amino acids, organo cations such as choline, nucleosides, inositols, vitamins, urea or anions, depending on the system. Members of the SSS family have been identified in bacteria, archaea and eukaryotes. Almost all functionally well-characterized members normally catalyze solute uptake via Na+ symport.
Howard Ronald Kaback was an American biochemist, known for Kabackosomes, the cell-free membrane transport vesicles. He was the brother of Michael M. Kaback, pediatrician and human geneticist, who developed a screening program to detect and prevent Tay–Sachs disease, a rare and fatal genetic disorder most common in Ashkenazi Jews.
Solute carrier family 9, subfamily B, member 2 is a protein that in humans is encoded by the SLC9B2 gene.
The amino acid-polyamine-organocation (APC) superfamily is the second largest superfamily of secondary carrier proteins currently known, and it contains several Solute carriers. Originally, the APC superfamily consisted of subfamilies under the transporter classification number. This superfamily has since been expanded to include eighteen different families.
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The ion transporter (IT) superfamily is a superfamily of secondary carriers that transport charged substrates.
The NhaB family belongs to the ion transporter (IT) superfamily. A representative list of proteins belonging to the NhaB family can be found in the Transporter Classification Database.
The NhaC family belongs to the Ion Transporter (IT) Superfamily. A representative list of proteins belonging to the NhaC family can be found in the Transporter Classification Database.
The NhaE family belongs to the Ion Transporter (IT) Superfamily, which has an end. A representative list of proteins belonging to the NhaE family can be found in the Transporter Classification Database.
The Monovalent Cation:Proton Antiporter-2 (CPA2) Family is a moderately large family of transporters belonging to the CPA superfamily. Members of the CPA2 family have been found in bacteria, archaea and eukaryotes. The proteins of the CPA2 family consist of between 333 and 900 amino acyl residues and exhibit 10-14 transmembrane α-helical spanners (TMSs).
The Monovalent Cation (K+ or Na+):Proton Antiporter-3 (CPA3) Family (TC# 2.A.63) is a member of the Na+ transporting Mrp superfamily. The CPA3 family consists of bacterial multicomponent K+:H+ and Na+:H+ antiporters. The best characterized systems are the PhaABCDEFG system of Sinorhizobium meliloti (TC# 2.A.63.1.1) that functions in pH adaptation and as a K+ efflux system, and the MnhABCDEFG system of Staphylococcus aureus (TC# 2.A.63.1.3) that functions as a Na+ efflux Na+:H+ antiporter.
Shimon Schuldiner is an Israeli biochemist. He has made important contributions to the understanding of proteins that couple the movement of ions and other molecules across membranes. Schuldiner is Mathilda Marks-Kennedy Professor at the Alexander Silberman Institute of Life Sciences, the Hebrew University of Jerusalem. He received a B.Sc. in 1967 and an M.Sc. in 1968 from the Hebrew University of Jerusalem, and a Ph.D. from the Weizmann Institute of Science in Rehovot in 1973.
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