Autophagy is a cellular mechanism used to regulate cell metabolism and to recycle or degrade damaged organelles and proteins. This is accomplished through the engulfment of cargo in a double-membrane structure called the autophagosome. The autophagosome fuses with the vacuole or the lysosome where hydrolytic enzymes facilitate the degradation of biomolecules. Each step of autophagy is a tightly regulated process from the recognition of cargo to the assembly of the autophagosome. ATG11 is an important scaffolding protein that seems to be involved in selective autophagy. Specifically, ATG11 facilitates the fusion of autophagosomal vesicles and the vacuole by linking selective autophagy receptors with a multiprotein complex consisting of ATG1-ATG13 (1). The ATG1-ATG13 complex is inactivated under normal conditions. Starvation triggers the binding of ATG17-ATG31-ATG29 to assemble a large pentameric complex capable of facilitating autophagosome assembly (2). ATG11 interacts with this protein complex to deliver the autophagosome to the vacuole. In addition ATG11 has been shown to bind ATG8, a component of the assembling autophagosome, thus linking newly assembled vesicles with general autophagy machinery (1). Recent research on ATG11 and its role in autophagosome-vacuole fusion has sought to identify additional components as well as the SNAREs involved in this process (2). These studies demonstrate importance of ATG11 during both autophagosome assembly and later during fusion with the vacuole.
Many of the studies deciphering the complex interaction networks rely on immunoprecipitation experiments (3). While often performed using epitope tags, ATG11 antibodies may enhance this approach by allowing these experiments to be done on the native proteins without any modifications. The same can be said for immunolocalization. Indirect immunofluorescence with ATG11 antibodies allows the examination of the native protein without any issues associated with the overexpression of GFP fusion proteins. Both approaches, using ATG11 antibodies as well as fusion proteins, were demonstrated by Tanaka et al. in their study of Hrr25, a kinase that can regulate the interaction of autophagy receptor proteins with ATG11 (4). In addition to these traditional uses, ATG11 antibodies are available as fluorophore conjugates to facilitate multiplex protein detection in western blot experiments. In addition to ATG11 antibodies, reagents are available to target many of the protein components involved throughout the autophagy process. Further studies with these research tools will help decipher the roles of these essential autophagy proteins.
PMIDs
