Membrantraffic

Membrantraffic, also called membrane trafficking, refers to the regulated transport of membrane components—lipids and proteins—within the cell between organelles and to the plasma membrane. This process distributes membrane cargo, supports organelle biogenesis, enables receptor recycling, nutrient uptake, and signal transduction, and maintains cellular homeostasis. Movement occurs via vesicular and tubular carriers that bud from donor membranes, traverse cytoskeletal tracks, and fuse with target membranes.

Key pathways include anterograde transport from the endoplasmic reticulum to the Golgi apparatus via COPII-coated vesicles, and retrograde transport from the Golgi back to the ER via COPI vesicles. Within the Golgi, enzymes and cargo are sorted for specific destinations. Endocytic routes bring material from the plasma membrane into endosomes, which mature and traffic to recycling compartments or lysosomes. Cargo sorting relies on adaptor proteins and coat complexes; vesicle budding and scission involve dynamin-related GTPases. Targeting and fusion depend on Rab GTPases, SNAREs, and tethering factors that ensure specificity, often aided by motor proteins moving along microtubules or actin filaments.

Regulation integrates signaling pathways and energy use from ATP and GTP hydrolysis, with quality control mechanisms in the ER and Golgi ensuring correct folding and sorting. Defects in membrantraffic components are linked to congenital disorders, neurodegenerative diseases, immunodeficiencies, and metabolic conditions. Research methods include fluorescence and electron microscopy, live-cell imaging, and genetic or pharmacological perturbations. Overall, membrantraffic is fundamental to cellular organization and function.