A bird's-eye view of autophagy.

Autophagy is a process in which a eukaryotic (but not prokaryotic) cell destroys its own components through the lysosomal machinery. This tightly regulated process is essential for normal cell growth, development, and homeostasis, serving to maintain a balance between synthesis and degradation, resulting in the recycling of cellular products. Here we try to expand the concept of autophagy and define it as a general mechanism of regulation encompassing various levels of the biosphere. Interestingly, one of the consequences of such an approach is that we must presume an existence of the autophagic processes in the prokaryotic domain.