Identification of novel retromer complexes in the mouse testis.

A family of vacuolar protein sorting (Vps) proteins, which are components of mammalian retromer complex, has been studied in the mouse. Vps26a is known as a retromer component that plays an important role in embryonic development: however, its cell-type expression and precise role remain to be elucidated. In this study, we identified a new isoform of Vps26a, called Vps26aT, which was expressed specifically in the mouse testis. Diverse expression patterns of Vps26 variants in mouse tissues were determined by Western blot and RT-PCR analyses, and the direct interaction of Vps26aT with Vps35 was also demonstrated by immunoprecipitation and pull-down assay using antibodies raised against each Vps component. Our results revealed that the retromer complex could be formed from different Vps26 isoforms in a tissue-specific manner, resulting in more than two types of the retromer complex, including the Vps26a-Vps29-Vps35, Vps26aT-Vps29-Vps35, and Vps26b-Vps29-Vps35 complexes in mouse tissues.