Endocitált

Endocitált describes a material that has been internalized by a cell through endocytosis. Endocytosis is a cellular process in which the plasma membrane engulfs extracellular material, forming vesicles that transport cargo into the cytoplasm. The term is used in cell biology, histology, and related fields to denote cargo after uptake. The English equivalent is endocytosed.

There are several forms of endocytosis. Phagocytosis, or cell eating, internalizes large particles or cells. Pinocytosis, or cell drinking, samples extracellular fluid and its solutes. Receptor-mediated endocytosis involves specific receptors that bind ligands, triggering vesicle formation; clathrin- or caveolin-mediated pathways are common examples. Macropinocytosis, which enlarges membrane ruffles to engulf fluid and solutes, is another mechanism. After vesicle formation, cargo is delivered to the endocytic system for processing.

Upon uptake, endocitált cargo is enclosed in endocytic vesicles that typically fuse with early endosomes. These compartments mature into late endosomes and often fuse with lysosomes for degradation. Some materials escape degradation and are released into the cytoplasm, while others are recycled back to the plasma membrane via recycling endosomes. Receptor-bound ligands may dissociate within endosomes, allowing receptors to be reused.

Endocytosis underpins nutrient uptake (for example, iron via transferrin and cholesterol via LDL), immune functions (phagocytosis by macrophages and antigen processing for MHC class II presentation), and regulation of receptor signaling. Disruptions in endocytic pathways can contribute to diseases and affect drug delivery and pharmacokinetics.

See also: endocytosis, endosome, lysosome, receptor-mediated uptake.