fagosomin

Fagosomin is a term used in cell biology to describe the membrane-bound vesicle that forms around a particle during phagocytosis. In English, the more common term is phagosome; "fagosomin" may appear in certain languages or older texts, but it refers to the same structure. Phagosomes are central to the innate immune response and to cellular cleanup processes.

Formation of a phagosome begins when phagocytic receptors bind a target, triggering cytoskeletal rearrangements that extend the plasma membrane around the particle. The enclosure pinches off to form a vesicle that contains the ingested material. Early events also set the stage for subsequent maturation.

During maturation, the phagosome undergoes a controlled sequence of fusions with endosomal and lysosomal compartments. This progression often involves Rab GTPases and other trafficking proteins, transitioning from early to late phagosomes and ultimately to a phagolysosome after fusion with lysosomes. The internal environment becomes acidic, driven by proton pumps, and hydrolytic enzymes are delivered to degrade the cargo.

Functions of phagosomes include digestion of microbes and debris, nutrient recovery, and, in professional antigen-presenting cells, processing of degraded components for display on MHC molecules. Some phagosomes also participate in generating antimicrobial reactive species to kill engulfed organisms.

Dysfunction in phagosome formation or maturation can lead to impaired microbial killing and contribute to infectious or inflammatory diseases. Pathogens have evolved strategies to interfere with phagosome maturation, illustrating the importance of this compartment in host defense.