Plays a role in vesicular protein sorting. Component of the membrane-associated retromer complex which is essential in endosome-to-Golgi retrograde transport. The VPS29-VPS26-VPS35 subcomplex may be involved in recycling of specific cargos from endosome to the plasma membrane. Component of the retromer complex which consists of VPS29 (MAG1), VPS26 (VPS26A or VPS26B), VPS35 (VPS35A or VPS35B or VPS35C), VPS5/17 (SNX1 or SNX2A or SNX2B). Component of a retromer subcomplex consisting of VPS29 (MAG1), VPS26 (VPS26A or VPS26B), VPS35 (VPS35A or VPS35B or VPS35C). Belongs to the VPS26 family.