| First Author | Tempel W | Year | 2004 |
| Journal | J Biol Chem | Volume | 279 |
| Issue | 28 | Pages | 29774-86 |
| PubMed ID | 15102839 | Mgi Jnum | J:91672 |
| Mgi Id | MGI:3050173 | Doi | 10.1074/jbc.M403065200 |
| Citation | Tempel W, et al. (2004) Structure of mouse Golgi alpha-mannosidase IA reveals the molecular basis for substrate specificity among class 1 (family 47 glycosylhydrolase) alpha1,2-mannosidases. J Biol Chem 279(28):29774-86 |
| abstractText | Three subfamilies of mammalian Class 1 processing alpha1,2-mannosidases (family 47 glycosidases) play critical roles in the maturation of Asn-linked glycoproteins in the endoplasmic reticulum (ER) and Golgi complex as well as influencing the timing and recognition for disposal of terminally unfolded proteins by ER-associated degradation. In an effort to define the structural basis for substrate recognition among Class 1 mannosidases, we have crystallized murine Golgi mannosidase IA (space group P2(1)2(1)2(1)), and the structure was solved to 1.5-A resolution by molecular replacement. The enzyme assumes an (alphaalpha)(7) barrel structure with a Ca(2+) ion coordinated at the base of the barrel similar to other Class 1 mannosidases. Critical residues within the barrel structure that coordinate the Ca(2+) ion or presumably bind and catalyze the hydrolysis of the glycone are also highly conserved. A Man(6)GlcNAc(2) oligosaccharide attached to Asn(515) in the murine enzyme was found to extend into the active site of an adjoining protein unit in the crystal lattice in a presumed enzyme-product complex. In contrast to an analogous complex previously isolated for Saccharomyces cerevisiae ER mannosidase I, the oligosaccharide in the active site of the murine Golgi enzyme assumes a different conformation to present an alternate oligosaccharide branch into the active site pocket. A comparison of the observed protein-carbohydrate interactions for the murine Golgi enzyme with the binding cleft topologies of the other family 47 glycosidases provides a framework for understanding the structural basis for substrate recognition among this class of enzymes. |
