Oligomerization

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The majority of the proteins and most of the membrane proteins will form an oligomer. It is important to determine the oligomeric state of membrane proteins, whether it is an enzyme, channels or receptors. This is because they often reveal structural evidence that bears on the possible quaternary association by defining or excluding them. For example, the x-ray structure reveals that an active site or transport channel is formed by monomers. In contrast, it is formed by more than one subunit, the relationship between quaternary structure and the function of the membrane proteins can be clarified. The x-ray structures f channel-forming proteins make clear distinctions between those which have channels in each subunit, such as trimeric porins and the family of aquaporins, and those in which different subunits contribute to one central channel, such as the potassium channels, the mechanosensitive channels, and the ToIC channel-tunnel.

Subunit interactions are also important for understanding the regulation of many hetero-oligomers. An obvious example is the ATP synthase because the F1-ATPase can function to synthesize ATP only when coupled to the F0 subunits in the membrane. High-resolution structures of increasing portions of the ATP synthase, in combination with a wealth of data from other studies, are now providing insight into how its components function together. The majority of the proteins and most of the membrane proteins will form an oligomer. It is important to determine the oligomeric state of membrane proteins, whether it is an enzyme, channels or receptors. This is because they often reveal structural evidence that bears on the possible quartenary association by defining or excluding them. For example, the x-ray structure reveals that an active site or transport channel is formed by monomers. In contrast, it is formed by more than one subunit, the relationship between quartenary structure and the function of the membrane proteins can be clarified. The x-ray structures f channel-forming proteins make clear distinctions between those which have channels in each subunit, such as trimeric porins and the family of aquaporins, and those in which different subunits contribute to one central channel, such as the potassium channels, the mechanosensitive channels, and the ToIC channel-tunnel[1].

References

  1. Membrane Structural Biology with Biochemical and Biophysical Foundations, Mary Luckey, page 309-310
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