The biophysical properties of the cell membrane are crucial for its functioning. In physiological conditions, the membrane is fluid, while it becomes gel-like at cooler temperatures. The lipid-protein composition of the cell membrane is highly varied, as is the thickness of the membrane. The high level of heterogeneity in the cell membrane is the result of the diversity of proteins and lipids in the cell, and local nonequilibrium effects.
What Are Cellular Membranes Made Of?
Proteins are a major constituent of the cell membrane. Proteins comprise half of the mass of most cellular membranes. Most of these proteins are transmembrane, which means that they stick out on both sides. They also have hydrophobic surface characteristics of cell membrane. As a result, the membranes function as gatekeepers for a cell’s internal activities.
Cell membranes can be prepared using several techniques. For example, sonication is a commonly used technique for preparing cell membrane sheets. However, this technique does not produce uniform membrane sheets due to the uneven shear stress it causes. Moreover, conventionally prepared cell membrane fragments do not allow accurate investigations of biological events on the intact cytoplasmic face.
The diversity of lipid species in the cell membrane suggests a large range of possible combinatorial interactions. Furthermore, the membranes of living cells cannot be homogeneous in length because of local variation in composition, asymmetric leaflet organization, and a difference in membrane thickness. Because cell membranes are far more complicated than model membranes, it has been possible to obtain more information about the interaction of proteins and lipids.