phospholipidische

Phospholipids are a class of lipids defined by a glycerol backbone with two fatty acid chains and a phosphate-containing head group. Their amphipathic nature—hydrophobic tails and a hydrophilic head—drives their self-assembly into lipid bilayers, the basic architecture of cellular membranes. The bilayer provides barrier function while allowing selective transport and hosting membrane proteins.

Common glycerophospholipids include phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI). Other important members are cardiolipin and plasmalogens. The head group chemistry and fatty acyl composition determine membrane surface charge, curvature, and fluidity, and tissues may show distinct phospholipid profiles.

Biosynthesis and metabolism: In eukaryotes, phospholipids are synthesized mainly in the endoplasmic reticulum. The Kennedy pathway generates PC and PE, while head-group exchange and Lands' cycle remodel acyl chains. Phospholipases A, C, and D hydrolyze phospholipids to release fatty acids and generate signaling lipids such as diacylglycerol (DAG) and inositol trisphosphate (IP3) from phosphatidylinositol 4,5-bisphosphate (PIP2).

Roles: Phospholipids form membranes that define organelles and compartments, contribute to membrane fusion and trafficking, and participate in signaling and recognition. Phosphatidylserine exposure on the outer membrane is a signal in apoptosis, while phosphoinositides regulate numerous signaling pathways and cytoskeletal dynamics. Alterations in phospholipid metabolism are associated with various diseases, including metabolic disorders and neurodegenerative conditions.