Gram-negative bacterial cell membrane

The **Gram-negative bacterial cell membrane**—more accurately termed the *outer membrane*—is a defining structural feature found exclusively in Gram-negative bacteria. It forms part of a multilayered envelope that also includes an inner cytoplasmic (plasma) membrane and a thin peptidoglycan layer sandwiched between them. The **outer leaflet** is rich in **lipopolysaccharide** (LPS), which acts both as an essential barrier against toxic compounds—including many antibiotics—and as an important virulence factor responsible for strong immune reactions when released into host tissues ("endotoxin"). The inner leaflet consists mainly of phospholipids. Embedded within this asymmetric bilayer are various proteins such as **porins**, which facilitate selective uptake of nutrients while restricting entry by harmful substances. Structural proteins like Braun’s lipoprotein anchor the peptidoglycan layer to the outer membrane, providing additional stability.[1][2][3][6] This complex architecture gives rise not only to unique staining properties under laboratory conditions but also underpins much of what makes these organisms challenging clinical pathogens—including their ability both to resist antibiotic penetration and provoke robust host immune responses.[1][2] Note on correctness/target status: The "Gram-negative bacterial cell membrane" is not considered a canonical therapeutic target like receptors or enzymes; it is instead an anatomical/structural feature composed itself out of multiple molecular components. If you seek information about druggable targets within this system—for example, "lipopolysaccharide," "porin," or specific transporters—those would be more appropriate entries for structured data extraction.[6]

Other names

Gram-negative outer membraneGram-negative cell envelope (sometimes used interchangeably, but technically refers to all layers)LPS-diderm (scientific term for bacteria with a lipopolysaccharide-containing outer membrane)[6]

For drugs like polymyxins: * Bind to LPS and phospholipids in the outer membrane, disrupting its integrity leading to increased permeability and cell death. For other antibiotics: * Must traverse the outer membrane via porin channels before reaching intracellular targets; resistance can arise from altered porin expression.