ATP-powered Pump

Ions, small hydrophilic molecules, lipids (ATP-powered pumps)... 

Three classes of transmembrane proteins mediate transport of ions, sugars, amino acids, and other metabolites across cell membranes ATP-powered pumps, channels, and transporters (see Figure 7-2). 

The general structures of the four classes of ATP-powered pumps are depicted in Figure 7-6, with specific examples in each class listed below. Note that the members of three classes (P, F, and V) transport ions only, whereas members of the ABC superfamily primarily transport small molecules. 

Name the four classes of ATP-powered pumps that produce active transport of ions and molecules. Indicate which of these classes transport ions only and which transport primarily small molecules. In the case of one class of these ATP-powered pumps, the initial discovery of the class came from stud3dng not the transport of a natural substrate but rather artificial substrates used as cancer chemotherapy drugs. What do investigators now think are common examples of the natural substrates of this particular class of ATP-powered pumps ... 

A detailed molecular understanding of how various transport proteins move lipids from one membrane leaflet to another (flippase activity) and Into and out of cells Is not yet In hand. Such understanding will undoubtedly require a determination of many high-resolutlon structures of these molecules, their capture In various stages of the transport process, and careful kinetic and other biophysical analyses of their function, similar to the approaches discussed In Chapter 7 for elucidating the operation of Ion channels and ATP-powered pumps. 

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