Vesikuly

Vesikuly, or vesicles in English, are small membrane-bound sacs that enclose a lumen and are surrounded by a lipid bilayer. They occur throughout the cytoplasm and at the cell surface and serve to transport and store molecules such as proteins, lipids, and signaling factors.

Formation and routing: Vesicles form by budding from donor membranes, aided by coat protein complexes. COPII drives transport from the endoplasmic reticulum to the Golgi apparatus, COPI mediates retrograde transport within the Golgi and back to the ER, and clathrin-coated vesicles participate in trafficking to endosomes, lysosomes, or the plasma membrane. Vesicles fuse with target membranes, delivering their contents.

Categories: Endocytic vesicles internalize extracellular material and deliver it to endosomes; secretory vesicles carry cargo for release by exocytosis, with regulated and constitutive pathways. Transport vesicles shuttle cargo between organelles and the plasma membrane. Specialized vesicles in neurons, called synaptic vesicles, store neurotransmitters for rapid release. Extracellular vesicles, including exosomes and microvesicles, are released into the extracellular space and mediate intercellular communication.

Size and composition: Vesicles vary in size from about 30 to 1000 nanometers and are composed of a phospholipid bilayer with embedded proteins that select cargo and mediate docking and fusion.

Clinical relevance: Defects in vesicle formation or trafficking contribute to diseases ranging from neurodegenerative disorders to metabolic syndromes and immunological conditions, underscoring vesicles' essential cellular roles.