Na+,K+-ATPase, also known as the Na+,K+-pump or the Na+pump, is present in all cells and is responsible for establishing the gradients of Na+ and K+ across the plasma membrane. These gradients provide energy for various essential cell functions. Composed of three subunits (α, β, and γ), Na+,K+-ATPase exists in the membrane with a stoichiometric composition of 1α, 1β, 1γ. The α subunit contains binding sites for Na+, K+, and ATP. It is also the subunit that binds cardiac glycosides (e.g., ouabain), which specifically inhibit the enzyme. It has a transmembrane domain and three intracellular domains: phosphorylation (P-domain), nucleotide binding (N-domain), and actuator (A-domain). While the α subunit is the functional unit of the enzyme, it cannot function without the β subunit. The β subunit is responsible for targeting the α subunit to the membrane and appears to modulate the affinity of Na+,K+-ATPase for Na+ and K+. The α and β subunits can carry out Na+ and K+ transport in the absence of the γ subunit, but the γ subunit seems to have a regulatory role. The γ subunit is a member of a family of proteins called FXYD proteins. 

H+-ATPase in the plasma membrane plays a crucial role in urinary acidification. 

ABC transporters are a diverse group of membrane transporters found in both prokaryotic and eukaryotic cells. They possess ATP-binding amino acid domains (ABC domains). To date, more than 40 specific transporters have been identified, belonging to seven subgroups of ABC transporters in humans. These transporters facilitate the transport of various molecules/ions, including Cl−, cholesterol, bile acids, drugs, iron, and organic anions. 

Membrane transporters are specific and regulated to allow the entry and exit of biologically important molecules. While some transporters are present in all cells (e.g., Na+,K+-ATPase), many others are limited to specific cell types. This specificity of expression tailors the function of the cell to its respective organ system. Additionally, the amount of a molecule being transported across the membrane can be regulated by altering the number or kinetics of individual transporters. This regulation can involve changes in the number of transporters in the membrane or the duration of time an ion channel remains open or closed. 

Cells can bring solute and water inside through endocytosis and release them through exocytosis. Endocytosis occurs when a portion of the plasma membrane pinches off and is internalized.
Na+,K+-ATPase(alsocalledtheNa+,K+-pump orjusttheNa+pump)isfoundinallcellsandisresponsibleforestablishingthegradientsofNa+ andK+ acrosstheplasmamembrane.Thesegradientsinturnprovideenergyforseveralessentialcellfunctions(see ).Na+,K+-ATPaseiscomposedofthreesubunits(α,β,andγ),andtheproteinexistsinthemembranewithastoichiometriccompositionof1α,1β,1γ.Theα subunitcontainsbindingsitesforNa+,K+ andATP.Itisalsothesubunitthatbindscardiacglycosides(e.g.,ouabain),whichspecificallyinhibittheenzyme.Ithasatransmembranedomainandthreeintracellulardomains:phosphorylation(P-domain),nucleotidebinding(N-domain),andactuator(A-domain).Althoughtheα subunitisthefunctionalsubunitoftheenzyme(i.e.,ithydrolyzesATP,bindsNa+ andK+ ,andtranslocatesthemacrossthemembrane),itcannotfunctionwithouttheβ subunit.Theβ subunitisresponsiblefortargetingtheα subunittothemembraneandalsoappearstomodulatetheaffinityoftheNa+,K+-ATPaseforNa+ andK+ .Theα andβ subunitscancarryoutNa+ andK+ transportintheabsenceoftheγ subunit.However,theγ subunitappearstoplayaregulatoryrole.Theγ subunitisamemberofafamilyofproteinscalledFXYD proteins (sonamedfortheFXYDaminoacidsequencefoundintheprotein).
H+-ATPase in the plasma membrane plays an important role in urinary acidification (see
ABC transporters represent a large group of membrane transporters. They are found in both prokaryotic and eukaryotic cells, and they have amino acid domains that bind ATP (i.e., ABC domains). Seven subgroups of ABC transporters in humans and more than 40 specific transporters have been identified to date. They transport a diverse group of molecules/ions, including Cl−, cholesterol, bile acids, drugs, iron, and organic anions.
Because biologically important molecules enter and leave cells through membrane transporters, membrane transport is specific and regulated. Although some membrane transporters are ubiquitously expressed in all cells (e.g., Na+,K+-ATPase), the expression of many other transporters is limited to specific cell types. This specificity of expression tailors the function of the cell to the organ system in which it is located (e.g., the sodium-glucose–linked transporters SGLT-1 and SGLT-2 in the epithelial cells of the intestines and renal proximal tubules). In addition, the amount of a molecule being transported across the membrane can be regulated. Such regulation can take place through altering the number of transporters in the membrane or altering the rate or kinetics of individual transporters (e.g., the time an ion channel stays in the open versus closed state), or both.
Solute and water can be brought into the cell through a process of endocytosis and released from the cell through the process of exocytosis. Endocytosis is the process whereby a piece of the plasma membrane pinches off and