membranecortex

Membranecortex, often referred to as the cell cortex or actin cortex, is a thin, dynamic layer on the cytoplasmic face of the plasma membrane. It comprises a network of actin filaments and associated proteins that lies just beneath the membrane, typically within a few hundred nanometers, and is intimately linked to many transmembrane proteins.

The core of the membranecortex is an actin-based cytoskeleton, organized and stabilized by a set of cross-linking and motor proteins. Key components include actin filaments, myosin motors, and a variety of cross-linkers such as filamin, α-actinin, and fascin. Membrane–cortex connections are reinforced by linker proteins, notably the ERM family (ezrin, radixin, moesin), as well as ankyrins and spectrins in some cell types, which help tether membrane proteins to the cortical actin network.

Functions of the membranecortex include maintaining cell shape and mechanical integrity, regulating membrane tension and diffusion of membrane proteins, and organizing the lateral distribution of receptors and channels. The cortex also participates in endocytosis and exocytosis, facilitates cell movement and polarization, and provides a scaffold for signaling pathways that coordinate cellular responses to the environment.

Dynamics and remodeling of the membranecortex are essential during processes such as cell migration, division, and shape changes. The network is continuously assembled and disassembled, allowing rapid responses to mechanical and chemical cues. Variations in cortical composition and organization contribute to differences among cell types, such as the specialized spectrin–actin cortex of red blood cells.

In research, membranecortex structure and function are studied through fluorescence and super-resolution microscopy, atomic force microscopy, and biophysical assays to understand how cortical mechanics influence cellular behavior.