Membrane trafficking between cellular compartments is a complex process involving a variety of factors including coat proteins, small GTPases, adaptors and acyl-CoA. The lipid modifying accessory proteins CtBP/BARS and endophilin, that use acyl-CoA as substrate, are also implicated. Here we present evidence that a novel, membrane-associated acyl-CoA binding protein, MAA-1, functions in maintaining normal morphology of the endosomal recycling compartments in C. elegans. Mutants lacking
maa-1 activity, accumulate multiple protrusions from the endosomal recycling compartment consistent with a requirement for vesicle fusion or fission. MAA-1 binds acyl-CoA in vitro and the function is dependent on its acyl-CoA binding ability. We have also investigated the involvement of the homologues of endophilin B,
erp-1, and CtBP/BARS,
ctbp-1, in vesicular trafficking. Mutants lacking
erp-1 and
ctbp-1 display a mildly uncoordinated phenotype and furthermore, like
maa-1, show defects in endosomal morphology. These results taken together favour a model, in which MAA-1 functions together with either ERP-1 or CTBP-1 during vesicle biogenesis.