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Which of the following is false about integrin structure and function?
Integrins have two subunits, alpha and beta. They do indeed bind the cell's cytoskeleton to its matrix, and can indicate to the cell the nature of that matrix. Integrins attach to a cell's actin and intermediate filaments. Blood platelets contain integrins, which bind proteins, like fibrinogen, in the matrix. This permits blood clotting, and the absence of certain integrins can cause a pathology in which people's blood does not clot well.
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Which of the following statements is true?
Transport proteins (such as the GLUT1 transporter) are asymmetric. They have two conformational states that accept the ligand from the extracellular environment and release it inside the cell after transport.
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Which of these transporters involves the formation of a high energy intermediate?
The sodium-potassium ATPase and the calcium-hydrogen ATPase (active transporters) are both correct and form high energy aspartyl phosphate intermediates inside the cell.
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The sodium-potassium pump is used in many different cells to control the concentration and movement of ions across the membrane. Which of the following is true about the sodium-potassium pump?
Many of the distractors have partially correct statements. In full, the sodium-potassium ATPase pump is an active exchanger, meaning it is a transporter that uses ATP to move two different ions across the membrane. In this case, the transporter hydrolyzes ATP to move 3 sodium ions out of the cell and 2 potassium ions into the cell. This means that with every transport the cell looses a negatively charged cation, making the cytosol a little more negatively charged.
The sodium-potassium pump often moves the molecules against their concentration gradients.
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