Epsin?like protein: a novel clathrin associated protein in Giardia lamblia.

FELIZIANI C; ZAMPONI N; MIRAS S; LANFREDI-RANGEL; TOUZ MC

Congreso; saib; 2012

The epsin N-terminal homology (ENTH) domain is an evolutionarily conserved protein module, which is found in proteins involved in clathrin-mediated trafficking. By searching in the GDB, we found that GlENTHp (Giardia lambliaENTHprotein) contains an ENTH domain that shares the 3D structure with human epsin ENTH domain, displaying an -helical structure composed of 7 -helices. This domain is present in epsin or epsin-related (epsinR) proteins, which are involved in endocytosis and protein trafficking from the Golgi to the lysosomes, respectively. Both, epsin and epsinR possess clathrin-binding motifs, but only epsin incorporates an ubiquitin-interaction motif. Using Giardia?s specific anti-clathrin and anti-ubiquitin Abs, we determined that GlENTHp interacts with both proteins. Subcellular localization showed that this protein is located mainly in the cytosol and occasionally in the nuclei. Biochemical analysis showed that GlENTHp binds PI(3,4,5)P and PI(4)P, linked to the plasma membrane and Golgi, respectively. Moreover, protein-protein interaction experiments showed that GlENTHp physically interacts with AP-2 (involved in endocytosis) and with AP-1 (implicated in the Golgi-to-lysosome trafficking). Altogether, these results suggest that GlENTHp participates in the machinery for clathrinmediated membrane budding, functioning as a dual epsin-epsinR protein.