Endosomal Compartments

Synonyms

Endolysosomal pathway; Endosomal protein sorting; Receptor-mediated endocytosis

Definition

In eukaryotic cells, receptor-mediated endocytosis releases cargo-loaded vesicles at the plasma membrane. The vesicle content passes through a series of discontinuous closed membrane systems called endosomal compartments. In a strict sense, endosomal compartments are temporal sorting stations where the fate of endocytosed cargo is determined.

Characteristics

Eukaryotic cells internalize a variety of extracellular material (cargo) either nonspecifically by phagocytosis and pinocytosis or selectively through receptor-mediated endocytosis. In phagocytosis, specialized cells (e.g., macrophagesand neutrophils) engulf large particles such as cell debris, bacteria, and viruses. Pinocytosis, exhibited by all cell types, involves uptake of extracellular fluid continually as tiny droplets (micropinocytosis) or sometimes as large droplets (macropinocytosis). By contrast, receptor-mediated...