| Modification Notes |
PMM1 (phosphomannomutase 1), also known as Sec53 or PMMH22, is a 262 amino acid protein that localizes to the cytoplasm and belongs to the eukaryotic PMM family. Expressed at high levels in brain, liver, pancreas and heart and present at lower levels in skeletal muscle, PMM1 catalyzes the conversion of alpha-D-mannose 1-phosphate to D-mannose 6-phosphate, an event that is required for a number of crucial mannosyl transfer reactions. The gene encoding PMM1 maps to human chromosome 22, which houses over 500 genes and is the second smallest human chromosome. Mutations in several of the genes that map to chromosome 22 are involved in the development of Phelan-McDermid syndrome, Neurofibromatosis type 2, autism and schizophrenia. |