Plasma membrane phospholipid bilayer (PM) (PM)

The plasma membrane phospholipid bilayer is a fundamental biological structure composed of two layers of amphipathic phospholipids, primarily phosphatidylcholine, phosphatidylethanolamine, and phosphatidylserine, which forms the primary boundary of the cell (StatPearls, 2023). It serves as a semi-permeable barrier that regulates the transport of ions, nutrients, and waste products while providing a stable yet fluid environment for membrane-bound proteins such as receptors, transporters, and enzymes (Molecular Biology of the Cell, 2014). The fluid-mosaic nature of the bilayer is essential for dynamic cellular processes, including signal transduction, vesicle trafficking, and cell motility. In various disease states, the integrity and composition of the bilayer are significantly altered; for instance, cancer cells often exhibit increased membrane fluidity and a loss of lipid asymmetry, while neurodegenerative diseases are frequently associated with lipid peroxidation and membrane damage (NCBI, 2021). Pharmacologically, the bilayer is a direct target for several classes of drugs, including polyene antifungals like Amphotericin B and lipopeptide antibiotics like Daptomycin, which induce pore formation and membrane depolarization to exert their effects (PubMed, 2020). Furthermore, the bilayer's biophysical properties are critical considerations in the development of lipid-based drug delivery systems, such as liposomes and lipid nanoparticles, which are designed to fuse with or bypass the cellular membrane (NIH, 2022).

Other names

Cell membraneCytoplasmic membranePlasmalemmaLipid bilayerCellular membrane

Drugs targeting the phospholipid bilayer typically act through physical disruption, such as pore formation (e.g., polyene antifungals) or detergent-like solubilization of the membrane (e.g., polymyxins). Other agents, such as general anesthetics, partition into the lipid phase to modulate the biophysical properties of the membrane (e.g., fluidity, thickness, and lateral pressure), which indirectly alters the function of embedded membrane proteins like ion channels and G protein-coupled receptors (StatPearls, 2023; PubMed, 2020).