Phagosome maturation: going through the acid test.

Phagosome maturation is the process by which internalized particles (such as bacteria and apoptotic cells) are trafficked into a series of increasingly acidified membrane-bound structures, leading to particle degradation. The characterization of the phagosomal proteome and studies in model organisms and mammals have led to the identification of numerous candidate proteins that cooperate to control the maturation of phagosomes containing different particles. A subset of these candidate proteins makes up the first pathway to be identified for the maturation of apoptotic cell-containing phagosomes. This suggests that a machinery that is distinct from receptor-mediated endocytosis is used in phagosome maturation.