Epsin 1 undergoes nucleocytosolic shuttling and its Eps15 interactor NH2-terminal homology (ENTH) domain, structurally similar to armadillo and HEAT repeats, interacts with the transcription factor promyelocytic leukemia Zn2+ finger protein (PLZF)

Epsin (Eps15 interactor) is a cytosolic protein involved in clathrin-mediat ed endocytosis via its direct interactions with clathrin, the clathrin adap tor AP-2, and Eps 15. The NH2-terminal portion of epsin contains a phylogen etically conserved module of unknown function, known as the ENTH domain (ep sin NH2-terminal homology domain),We have now solved the crystal structure of rat epsin 1 ENTH domain to 1.8 Angstrom resolution. This domain is struc turally similar to armadillo and Heat repeats of beta-catenin and karyopher in-beta, respectively. We have also identified and characterized the intera ction of epsin 1, via the ENTH domain, with the transcription factor promye locytic leukemia Zn2+ finger protein (PLZF), Leptomycin B, an antifungal an tibiotic, which inhibits the Crm1-dependent nuclear export pathway, induces an accumulation of epsin 1 in the nucleus. These findings suggest that eps in 1 may function in a signaling pathway connecting the endocytic machinery to the regulation of nuclear function.