Purification, crystallization and preliminary X-ray crystallographic analysis of recombinant murine Golgi mannosidase IA, a class I alpha-mannosidase involved in Asn-linked oligosaccharide maturation.

Golgi mannosidase IA is a class I alpha-mannosidase which catalyzes the conversion of Man9GlcNAc2 or Man8GlcNAc2 oligosaccharide substrates to Man5GlcNAc2 during the maturation of Asn-linked oligosaccharides. The enzyme is a type II membrane protein, and a recombinant form of mannosidase IA from mouse, lacking the transmembrane domain, has been expressed in Pichia pastoris, purified to homogeneity and crystallized by the hanging-drop vapor-diffusion method. The crystals grow as thin rods, with unit-cell dimensions a = 54.9, b = 135.01, c = 69.9 A. The crystals exhibit the symmetry of space group P2221 and diffract to 2.8 A resolution. The asymmetric unit contains one monomer ( approximately 53 kDa) and has a solvent content of 59%.