vesikulsystem

Vesikulsystem (often rendered in English as the vesicle system or vesicular transport system) is the cellular network of membrane-bound vesicles and associated organelles that mediate trafficking of lipids, proteins and other cargo within eukaryotic cells. It comprises transport vesicles, the endoplasmic reticulum, the Golgi apparatus, endosomes, lysosomes and the plasma membrane, and is often described as part of the broader endomembrane system.

Vesicular transport relies on the formation (budding), movement and fusion of membrane-enclosed carriers. Coat proteins such as clathrin, COPI and COPII select cargo and shape nascent vesicles; small GTPases (notably Rab proteins) and motor proteins direct vesicle movement along cytoskeletal tracks; and SNARE proteins mediate specific membrane fusion events. These coordinated steps ensure directionality and specificity of intracellular trafficking.

Functions of the vesicle system include secretion (exocytosis), uptake and recycling of membrane components (endocytosis), delivery of enzymes to lysosomes, and rapid regulated release in specialized cells (for example, synaptic vesicles in neurons or hormone secretion in endocrine cells). Proper vesicular trafficking is essential for membrane homeostasis, signaling and protein maturation.

Dysfunction of the vesicle system contributes to diverse diseases, including neurodegenerative disorders, lysosomal storage diseases and certain congenital trafficking disorders. The system is studied using microscopy, biochemical fractionation and molecular genetics to reveal mechanisms of cargo sorting, vesicle dynamics and their roles in cell physiology.