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 cargo selection. H2O + O-phospho-L-serine = L-serine + phosphate H2O + O-phospho-D-serine = D-serine + phosphate Binds 2 Zn(2+) ions per subunit. Component of a retromer subcomplex consisting of vps29, vps26 and vps35. Belongs to the VPS29 family.