Fig. 3

Increased expression of endocytosis-related protein families and analysis of specific endocytic motifs within the Pmp and BspA protein family. a Expression levels of several protein families involved in endocytosis are represented as bubbles and compared among the trichomonads. Although T. vaginalis again shows the highest numbers, all gene families are expanded in the trichomonads compared to Giardia intestinalis another anaerobic human parasite. In particular, the Rab subfamily of the small GTPases displays a specific expansion in transcription among the trichomonadida as obvious by comparing those numbers to the human gene family. b The trichomonad Pmp and BspA families were screened for the presence of a transmembrane domain and further for specific endocytic motifs within their cytoplasmic tails. While 90% of the T. vaginalis Pmps carry a TMD it is just around a quarter for the BspAs. Notably, in Tri. batrachorum, which showed a similar expansion of this protein family, only around 3% exhibit a TMD. The fraction of proteins with motifs involved in endocytic processes is diverse. However, the T. vaginalis proteins possess an increased amount of specific motifs e.g. the NPx[YF]. c Sequence alignment of T. vaginalis Pmp and BspA proteins with focus on the C-terminal region. Together with the conserved transmembrane domain those proteins [with one exception (TVAG_240680)] also carry the T. vaginalis specific NPx[YWF] motif and an acidic cluster within their cytoplasmic tails