Transport

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Primary active transport

Example of primary active transport
Primary active transport, also called direct active transport, directly uses energy to transport molecules across a membrane.
Most of the enzymes that perform this type of transport are transmembrane ATPases. A primary ATPase universal to all cellular life is the sodium-potassium pump, which helps to maintain the cell potential. Other sources of energy for Primary active transport are redox energy and photon energy (light). An example of primary active transport using Redox energy is the mitochondrial electron transport chain that uses the reduction energy of NADH to move protons across the inner mitochondrial membrane against their concentration gradient. An example of primary active transport using light energy are the proteins involved in photosynthesis that use the energy of photons to create a proton gradient across the thylakoid membrane and also to create reduction power in the form of NADPH.
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ATP utilizing Primary active transport types
(1) P-type ATPase : Sodium potassium pump, Calcium pump, Proton pump
(2) F-ATPase : mitochondrial ATP synthase, Chloroplast ATP synthase
(3) V-ATPase : vacuolar ATPase
(4) ABC (ATP Binding Cassette) transporter : MDR, CFTR, etc
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P-type ATPase
The P-type ATPases, also known as E1-E2 ATPases, are a large group of evolutionarily related ion pumps that are found in bacteria, archaea andeukaryotes. They are α-helical bundle primary transporters referred to as P-type ATPases because they catalyze auto- (or self-) phosphorylation of a key conserved aspartate residue within the pump. In addition, they all appear to interconvert between at least two different conformations, denoted by E1 and E2.
Most members of this transporter family are specific for the pumping of a large array of cations, however one...