Primary active transport

Primary active transport is a type of active transport that involves the direct use of metabolic energy to transport molecules across a membrane. Most of the enzymes that perform this type of transport are transmembrane ATPases.

Mechanism

Primary active transport, also called direct active transport, directly uses energy to transport molecules across a membrane. This energy is derived from adenosine triphosphate (ATP). During this process, ATP is hydrolyzed to produce phosphate and adenosine diphosphate. The energy released from this reaction is used to transport molecules against their concentration gradient.

Types

There are several types of primary active transport systems:

• Sodium-Potassium ATPase - This system, which is found in the plasma membrane of many cells, pumps sodium out of the cell and potassium into the cell.
• Hydrogen-Potassium ATPase - This system, which is found in the stomach lining, pumps hydrogen into the stomach, creating the highly acidic environment necessary for the digestion of food.
• Calcium ATPase - This system, which is found in the sarcoplasmic reticulum of muscle cells, pumps calcium into the sarcoplasmic reticulum, allowing for muscle contraction.

Role in disease

Abnormalities in primary active transport can lead to a variety of diseases. For example, defects in the Sodium-Potassium ATPase can lead to high blood pressure and heart failure. Similarly, defects in the Hydrogen-Potassium ATPase can lead to peptic ulcers and GERD.

See also

• Secondary active transport
• Passive transport
• Membrane transport protein

References

Primary active transport Resources
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