Autophagy is a complex cellular process that involves dynamic membrane rear
rangements under a range of physiological conditions. It is a highly regula
ted process that plays a role in cellular maintenance and development, and
has been implicated in a number of genetic diseases. Upon induction of auto
phagy, cytoplasm is sequestered into vesicles and delivered to a degradativ
e organelle, the vacuole in yeast or the lysosome in mammalian cells. The p
rocess is unique in that it converts material that is topologically intrace
llular into topologically extracellular. Autophagy was first described more
than 50 years ago, but it is since the discovery of the pathway in yeast c
ells that our knowledge about the molecular events taking place during the
process has expanded. The generation of autophagy-specific mutants in a var
iety of yeast cell lines has provided insight into functional roles of more
than 15 novel genes, double that number if we include genes whose products
function also in other processes. Although we have learned much about auto
phagy, many questions remain to be answered. This review highlights the mos
t recent advances in the autophagy field in both yeast and mammalian cells.