membranebound

Membrane-bound is a term used in biology to describe molecules, organelles, or complexes that are associated with biological membranes, typically the lipid bilayer that encloses cells or organelles. In common usage, membrane-bound refers to components that are anchored to or embedded in membranes, as opposed to soluble, cytosolic equivalents.

Membrane-bound components include two broad categories: proteins and organelles. Proteins may be integral membrane proteins that span the lipid bilayer, or peripheral membrane proteins that attach to the membrane surface through electrostatic interactions or covalent lipid modifications. Post-translational lipid attachments such as myristoylation, palmitoylation, or prenylation help anchor proteins to membranes. Membrane-bound ribosomes belong to the rough endoplasmic reticulum in eukaryotes and synthesize secreted and membrane proteins. Membrane-bound enzymes participate in processes at the surface of membranes or within membrane compartments, including transport, signaling, and metabolism.

Membrane-bound organelles are enclosed by membranes and include the nucleus (nuclear envelope), endoplasmic reticulum, Golgi apparatus, mitochondria, chloroplasts, lysosomes, peroxisomes, and vesicles. The compartmentalization afforded by membranes enables distinct biochemical environments, selective transport, and coordinated signaling. Disruption of membrane binding can affect protein function, trafficking, and cellular homeostasis.

The term membranebound is sometimes used as an alternative spelling in texts or databases, though membrane-bound remains the standard form in most modern literature.