The pump protein binds a specific solute and hydrolyzes ATP directly.
| | Location | Substrates | Stoichiometry | Inhibitor | | :--- | :--- | :--- | :--- | :--- | | Na⁺/K⁺ ATPase | Plasma membrane | Na⁺, K⁺ | 3 Na⁺ out / 2 K⁺ in / 1 ATP | Ouabain | | Ca²⁺ ATPase (PMCA) | Plasma membrane | Ca²⁺ | 1 Ca²⁺ out / 1 ATP | – | | Ca²⁺ ATPase (SERCA) | SR/ER membrane | Ca²⁺ | 2 Ca²⁺ into SR / 1 ATP | Thapsigargin | | H⁺/K⁺ ATPase | Gastric parietal cell | H⁺, K⁺ | 1 H⁺ out / 1 K⁺ in / 1 ATP | Omeprazole (proton pump inhibitor) | | H⁺ ATPase (V-type) | Lysosomal/vacuolar membrane | H⁺ | ~2 H⁺ in / 1 ATP | Bafilomycin A₁ | | ABC (e.g., MDR1) | Plasma membrane | Drugs / lipids | 1 substrate out / 2 ATP | – | active transport pumps
| | Role of Active Transport Pumps | | :--- | :--- | | Nerve conduction | Na⁺/K⁺ ATPase restores ion gradients after action potential. | | Muscle contraction & relaxation | Ca²⁺ ATPase pumps Ca²⁺ back into SR. | | Kidney function | Na⁺/K⁺ ATPase drives reabsorption of glucose, amino acids, and water. | | Acid-base balance | H⁺ ATPase in renal intercalated cells (acid secretion). | | Drug resistance | ABC transporters (MDR1) pump out antibiotics/chemotherapy agents. | | Digestion | H⁺/K⁺ ATPase in gastric parietal cells (stomach acid secretion). | The pump protein binds a specific solute and
Located in the membranes of vacuoles, lysosomes, and endosomes. Proton movement: They pump hydrogen ions ( H+cap H raised to the positive power ) exclusively into organelles. | | Kidney function | Na⁺/K⁺ ATPase drives