Rabbit Anti-Human RAB33B Polyclonal antibody

Autophagy (particularly macroautophagy) is a bulk degradation process used by eukaryotic cells in order to maintain adequate energy levels and cellular homeostasis through the delivery of long-lived proteins and organelles to the lysosome, resulting in their degradation. It is becoming increasingly clear that many of the molecular requirements to fulfil autophagy intersect with those of conventional and unconventional membrane trafficking pathways. Of particular interest is the dependence of these processes on multiple members of the Rab family of small GTP binding proteins. Rab33b is a protein that localises to the Golgi apparatus and has suggested functions in both membrane trafficking and autophagic processes. Interestingly, mutations in the RAB33B gene have been reported to cause the severe skeletal disorder, Smith-McCort Dysplasia; however, the molecular basis for Rab33b in this disorder remains to be determined. In this review, we focus on the current knowledge of the participation of Rab33b and its interacting partners in membrane trafficking and macroautophagy, and speculate on how its function, and dysfunction, may contribute to human disease.

Atg16L is a factor that is essential for elongation of the isolation membrane (also called phagophore), a precursor of the autophagosome. Atg16L facilitates LC3/Atg8-conjugation to phosphatidylethanolamine by forming an oligomeric complex with Atg12-conjugated Atg5 and recruiting an LC3-Atg3 intermediate to elongating isolation membranes. Although Atg16L is responsible for the isolation membrane localization of the complex, the mechanism by which Atg16L is targeted to or recognizes isolation membranes remains largely unknown. We recently reported finding that Atg16L specifically and directly interacts with the Golgi-resident small GTPase Rab33B (and Rab33A) via the coiled-coil domain of Atg16L. Since expression of a GTPase-deficient mutant of Rab33B or the coiled-coil domain of Atg16L modulates macroautophagy (simply referred to as autophagy below), Atg16L (or the Atg12-5/16L complex) is likely to function as a specific effector molecule for Rab33 in autophagosome formation. Future study of the cross talk between Atg16L-mediated autophagosome formation and Rab33-mediated membrane trafficking should provide an important clue to unresolved issues in autophagosome formation, specifically, the membrane source of autophagosomes.