Membranekrumning

Membranekrumning is a biological process in which biological membranes actively change shape to form folds, invaginations, or protrusions. The term originates from Danish, combining “membran” (membrane) and “krumning” (bending or curling). It pertains mainly to cellular membranes such as the plasma membrane, endoplasmic reticulum, mitochondria, and vesicular structures.

The process is driven by lipid composition, cytoskeletal forces, protein scaffolds, and curvature-inducing proteins. Lipid asymmetry, with different lipid types preferentially located on either side of the bilayer, creates spontaneous curvature. Proteins such as BAR-domain proteins, dynamin, and clathrin can bind to membranes, impose curvature by scaffolding or exerting mechanical force. Actin polymerization and microtubule motors can also generate pulling or pushing forces that contribute to membrane deformation.

Membranekrumning has several functional roles. It is essential for endocytosis and exocytosis, where the plasma membrane invaginates or layers out to transport materials in and out of the cell. During organelle biogenesis, such as the formation of the Golgi apparatus or mitochondria, membrane curvature underlies the creation of stacks, cristae, and tubular networks. The process also plays a role in cell division, where the division septum requires dynamic membrane folding. Defects in curvature regulation have been linked to diseases such as neurodegeneration, cancer metastasis, and viral entry disorders.

Research on membrane curvature is interdisciplinary, combining cell biology, biophysics, and computational modeling. Advances in cryo-electron microscopy, super-resolution imaging, and molecular dynamics simulations have clarified how specific proteins and lipid arrangements interact to produce the necessary mechanical features of membranekrumning.