s-YQII-HA was observed. To analyze whether the expression of the transgenic cells affected Giardia growth, time-course curves were performed using GlVps10, wild-type, and GlVps-YQII cells and no significant effect or cell deterioration was observed at 48 h of culturing. We recently showed that transport along the vacuolar pathway requires clathrin and the adaptors AP1 or AP2, with AP1 being involved in the forward lysosomal protein trafficking to the PVs, while AP2 participates in endocytosis. Unlike yeast and mammalian cells, Giardia does not contain GGAs homologous proteins, making AP1 the primary candidate for GlVps transport. To analyze whether AP1 is involved in GlVps trafficking, dsRNAma transgenic trophozoites were cotransfected with the plasmid expressing GlVps-HA. Thus, we were able to analyze the expression and localization of DMXAA GlVps-HA in trophozoites containing the m1 subunit of AP1 and in trophozoites expressing a reduced amount of m1. Densitometric analysis of RTPCR experiments showed that, when these trophozoites were induced with 10 mg/ml of tetracycline, the m1-antisense PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/22212322 8 Giardia Hydrolase Receptor RNA was present in 2m1 but not in +m1 or wild-type cells. Furthermore, a significant reduction of the endogenous m1 was observed in 2m1 trophozoites compared with +m1 or wt cells when the 39 endogenous segment of m1 was tested, supporting our previous results showing that production of m1dsRNA successfully diminished the transcript levels of m1 mRNA. No alteration on the glvps mRNA expression was observed between the 2m1, +m1 or wt cells. However, IFA and confocal microscopy showed that GlVps-HA was present as a distinctive punctuate pattern in 2m1 cells whereas the perinuclear/reticular localization of GlVps-HA in +m1 cells was conserved. Immunoblotting showed that degradation of the receptor GlVps-HA occurred in the transgenic 2m1 cells when compared with +m1 cells and differed from the processing observed for GlVps-YQII-HA in cells containing m1. Evidence of an interaction between the GlVps and AP1 was obtained in the yeast two-hybrid system. Initial analysis demonstrated that GlVps strongly interacted with m1. Moreover, GlVps-YQII provided no response. When the interaction between GlVps and m2 was tested, no positive results were obtained. Altogether these results suggest that GlVps protein trafficking depends on its tyrosinemotif, which is capable of binding AP1 but not AP2 for this purpose. GlVps is the presumed AcPh receptor When GlVps-HA was co-expressed with AcPh-V5 and analyzed with IFA and confocal microscopy, we observed that GlVps-HA and AcPh-V5 colocalized around the nuclei and also in some PVs. Correlation values indicate a significant degree of colocalization for both proteins. To test directly for the association of GlVps and AcPh, we performed yeast two-hybrid assays. After co-transformation and colony growth assays, we observed that GlVps and GlVps-YQII certainly interacted with AcPh, allowing the yeast reporter to grow in stringent growth medium. However, this interaction seemed not to be strong, since no colonies were obtained in highstringency growth medium. These results, in addition to the pulldown findings, suggest that GlVps 
and AcPh interact and may be transported together toward the PVs. The role of GlVps in transport was further tested by inhibition of GlVps expression by antisense production. Semiquantitative reverse transcription-PCR revealed an increase of the GlVps-antisense RNA production as
