Direct interaction between metastasis-associated protein 1 and endophilin 3.

The yeast two-hybrid system was used to search for partners of mouse metastasis-associated protein 1 (Mta1). Screening of a cDNA library prepared from mouse embryo yielded positive clones coding for endophilin 3. The site of interaction was suggested to be the SH-3-binding domain of Mta1 and SH-3 domain of endophilin 3. This interaction was confirmed by GST pull-down assay in vitro and immunoprecipitation in vivo. The Mta1 and endophilin 3 transcripts were highly expressed in testis and brain. But, Mta1 localized mainly in nucleus and to a lesser extent in cytoplasm while endophilin 3 localized mainly in cytoplasm. If Mta1 functions in cytoplasm, it might be involved in the regulation of endocytosis mediated by endophilin 3.