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Lodish H, Berk A, Zipursky SL, et al. Molecular Cell Biology. 4th edition. New York: W. H. Freeman; 2000.

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Molecular Cell Biology. 4th edition.

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Table 15-2Comparison of Major Classes of ATP-Powered Ion and Small-Molecule Pumps

P ClassF ClassV ClassABC Class
Substances Transported
H+, Na+, K+, Ca2+H+ onlyH+ onlyIons and various small molecules
Structural and Functional Features
Large catalytic α subunits (often two) become phosphorylated during solute transport; smaller β subunits may regulate transport.Multiple transmembrane and cytosolic subunits generally function to synthesize ATP on β cytosolic subunits powered by movement of H+ down an electrochemical gradient.Multiple transmembrane and cytosolic subunits generally use energy released by ATP hydrolysis to pump H+ ions from cytosol to organelle lumens, acidifying them.Two transmembrane domains form the pathway for solute; two cytosolic ATP-binding domains couple ATP hydrolysis to solute movement. Domains may be in one or separate subunits.
Location of Specific Pumps
Plasma membrane of plants, fungi, bacteria (H+ pump)Bacterial plasma membranesVacuolar membranes in plants, yeast, other fungiBacterial plasma membranes (amino acid, sugar, and peptide transporters)
Plasma membrane of higher eukaryotes (Na+/K+ pump)Inner mitochondrial membraneEndosomal and lysosomal membrane in animal cellsMammalian endoplasmic reticulum (transporters of peptides associated with antigen presentation by MHC proteins)
Apical plasma membrane of mammalian stomach cells (H+/K+ pump)Thylakoid membrane of chloroplastPlasma membrane of certain acid-secreting animal cells (e.g., osteoclasts and some kidney tubule cells)
Plasma membrane of all eukaryotic cells (Ca2+ pump)Mammalian plasma membranes (transporters of small molecules, phospholipids, small lipidlike drugs)
Sarcoplasmic reticulum membrane in muscle cells (Ca2+ pump)

From: Section 15.5, Active Transport by ATP-Powered Pumps

Copyright © 2000, W. H. Freeman and Company.


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