Biological Membranes - A. N. Ogurtsov 2012

Structure and Functions of Biomembranes
Intermolecular Interactions in Biomembranes
Protein-Protein Interactions

Protein-Structure/156.html">Protein Interactions manifest in membranes as reversible intramembrane aggregation of Membrane Proteins, often accompanied by Changes in the functional and enzymatic activity of the system. For example, intramembrane protein particles are uniformly distributed in Erythrocyte membranes and undergo reversible aggregation at pH values below 5.5. This aggregation is sensitive to the COMPOSITION OF THE aqueous phase; as electrolyte concentrations increase and pH levels drop, aggregation is inhibited. This intramembrane aggregation of protein particles in erythrocytes correlates with changes in the distribution of surface receptors.

It is now established that cycles of protein aggregation and disaggregation in Cell membranes are a widespread phenomenon, occurring in the following cellular processes:

1) pinocytosis;

2) at various Stages of the Cell Cycle;

3) during membrane interaction and fusion.

It is believed that aggregation interactions may be driven by the following phenomena:

a) electrostatic forces;

b) more complex intermolecular interactions governed by the Specific features of the lipid environment surrounding the proteins;

c) local crystallization of Lipids within membranes.

METABOLISM/35.html">Selection/41.html">Review Questions and Exercises

1. Describe the experiment that proved the existence of lipid-protein island clusters.

2. What is meant by the microheterogeneity of a biomembrane?

3. What four types of intermolecular interactions determine the state of lipids in Biomembranes?

4. What role do Hydration forces play in the interaction between phospholipid membranes?

5. How does the labile system of Hydrogen Bonds between lipid molecules block the destabilizing effect of electrostatic repulsion forces between the polar lipid headgroups?

6. How does the difference in hydrocarbon chain lengths of phospholipid molecules relate to the number of phase transitions observed in a membrane composed of these Phospholipids?

7. What Three types of Lipid-Protein Interactions exist in biomembranes?

8. How does the interaction of proteins with lipid monolayers affect protein function? Provide Examples.

9. What are annular lipids, and how do they affect the function of membrane proteins?

10. The activity of which membrane Enzymes depends on the presence of a lipid environment?

11. How is the lipid dependence of membrane enzyme activity recorded experimentally?

12. In which cellular processes do protein-protein interactions manifest as cycles of protein aggregation and disaggregation?

13. What three types of phenomena may underlie protein-protein aggregation interactions in biomembranes?



Last update: 13/08/2026

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