The 3-dimensional structure of lysosomal α-mannosidase. Peptides are coloured a-red, b-orange, c-yellow, d-green and e-blue. The active site is denoted by a Zn++ ion. Two mutant sites are displayed, demonstrating the effect of mutations c.215A>T: p.H72L affecting Zn++ coordination in the actives site (group 1 mutation, see text for explanation) and the prevalent mutation c.2248C>T: p.R750W which is likely affecting peptide e-d interaction (group 2 mutation, see text for explanation). The figure was kindly provided by Dr. P. Heikinheimo, University of Helsinki, Finland. It has been prepared with the program PyMol .