In biology, an ion transporter, also called an ion pump, is a transmembrane protein

Transmembrane protein

A transmembrane protein is a protein that goes from one side of a membrane through to the other side of the membrane. Many TPs function as gateways or "loading docks" to deny or permit the transport of specific substances across the biological membrane, to get into the cell, or out of the cell as...

 that moves ions across a plasma membrane against their concentration gradient, in contrast to ion channels, where ions go through passive transport

Passive transport

Passive transport means moving biochemicals and other atomic or molecular substances across membranes. Unlike active transport, this process does not involve chemical energy, because, unlike in an active transport, the transport across membrane is always coupled with the growth of entropy of the...

. These primary transporters are enzymes that convert energy from various sources, including ATP, sunlight, and other redox reactions, to potential energy stored in an electrochemical gradient. This energy is then used by secondary transporters, including ion carriers and ion channels, to drive vital cellular processes, such as ATP synthesis.

Energy source

Such ion pumps can use energy from a variety of sources, including ATP

Adenosine triphosphate

Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

 or the concentration gradient of another ion (sometimes called an "ion exchanger"). Symporter

Symporter

A cotransporter is an integral membrane protein that is involved in secondary active transport. It works by binding to two molecules or ions at a time and using the gradient of one solute's concentration to force the other molecule or ion against its gradient....

s transport anions down their concentration gradient to fuel the transport of another type of ion in the same direction, while antiporter

Antiporter

An antiporter is an integral membrane protein involved in secondary active transport of two or more different molecules or ions across a phospholipid membrane such as the plasma membrane in opposite directions.In secondary active transport, one species of solute moves along its electrochemical...

s also use the concentration gradient in this same manner but transport in the opposite direction. In contrast, uniporters transport a single ion down it’s concentration gradient. In all of these cases, there is at least one driving ion that travels down its concentration gradient, thereby providing the energy of the system. Ions that are moved up their concentration gradients are called the driven ion. For a more detailed description of one particular kind of ion pump, see Na⁺/K⁺-ATPase.

See also

• Wikipedia:MeSH D12.776#MeSH D12.776.157.530.450 --- ion pumps
• Transport protein
  Transport protein
  A membrane transport protein is a membrane protein involved in the movement of ions, small molecules, or macromolecules, such as another protein across a biological membrane. Transport proteins are integral membrane proteins; that is they exist within and span the membrane across which they...
  
  
  • Sodium-chloride symporter
    Sodium-chloride symporter
    The sodium-chloride symporter is a cotransporter in the kidney which has the function of reabsorbing sodium and chloride ions from the tubular fluid into the cells of the distal convoluted tubule of the nephron.It is a member of the SLC12...
    
    
  • Sodium-calcium exchanger
    Sodium-calcium exchanger
    The sodium-calcium exchanger is an antiporter membrane protein that removes calcium from cells. It uses the energy that is stored in the electrochemical gradient of sodium by allowing Na+ to flow down its gradient across the plasma membrane in exchange for the countertransport of calcium ions...
    
    
  • Plasma membrane Ca²⁺ ATPase
  • Neurotransmitter transporter
    Neurotransmitter transporter
    Neurotransmitter transporters are a class of membrane transport proteins that span the cellular membranes of neurons. Their primary function is to carry neurotransmitters across these membranes and to direct their further transport to specific intracellular locations...
    
    
    • Glutamate transporter
      Glutamate transporter
      Excitatory amino-acid transporters , formerly known as Glutamate transporters, belong to the family of neurotransmitter transporters. They serve to terminate the excitatory neurotransmitter signal by removal of glutamate from the neuronal synapse into Glia cells.In details, the EAATs are...
      
      
    • Monoamine transporter
      Monoamine transporter
      Monoamine transporters are protein structures that function as integral plasma membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. Three major classes of MATs are responsible for the reuptake of their associated amine neurotransmitters...
      
      
      • Dopamine transporter
        Dopamine transporter
        The dopamine transporter is a membrane-spanning protein that pumps the neurotransmitter dopamine out of the synapse back into cytosol, from which other transporters sequester DA and NE into vesicles for later storage and release...
        
        
      • Norepinephrine transporter
        Norepinephrine transporter
        The norepinephrine transporter , also known as solute carrier family 6 member 2 , is a protein that in humans is encoded by the SLC6A2 gene....
        
        
      • Serotonin transporter
        Serotonin transporter
        The serotonin transporter is a monoamine transporter protein.This protein is an integral membrane protein that transports the neurotransmitter serotonin from synaptic spaces into presynaptic neurons. This transport of serotonin by the SERT protein terminates the action of serotonin and recycles it...