Mannose 6-phosphate receptor homology (MRH) domain-containing lectins in the secretory pathway

► Recycling receptors, ER proteins, and a glycosyltransferase contain MRH domain. ► Many MRH domains function as lectins and bind mannose-containing N-glycans. ► Structures are known for ten MRH domains, revealing conservation of a similar fold. ► OS-9 and the MPR use the same four residues (Gln, Arg, Glu, Tyr) to bind mannose.