Identification and localization of two mouse phosphomannomutase genes, Pmm1 and Pmm2

Phosphomannomutases: catalyze the reversible conversion of mannose 6-phosph ate to mannose 1-phosphate. In humans, two different isozymes have recently been identified, PMM1 and PMM2. We have previously shown that mutations in the PMM2 gene cause the most frequent type of the congenital disorders of glycosylation, CDG-Ia. Here, we present data on the two mouse orthologous g enes, Pmm1 and Pmm2. The chromosomal localization of the two mouse genes ha s been determined. We also present the gene structure and the exon-intron o rganization of Pmm1 and Pmm2. Pmm1 maps to mouse chromosome 15, Pmm2 to chr omosome 16. These chromosomal regions are syntenic with regions on human ch romosomes 22 and 16, respectively. The Pmm1 gene is composed of eight exons and spans approximately 9.5 kb. The genomic structure is extremely well co nserved between the human and mouse gene. The Pmm2 gene consists of eight e xons acid spans a larger genomic region (approximate to 20 kb). An alignmen t of the human and mouse protein sequences confirms the conservation among this family of phosphomannomutases. The two mouse genes are expressed in ma ny tissues, but the expression pattern is slightly different between Pmm1 a nd Pmm2. The most striking difference is the high expression of Pmm1 in bra in tissue. whereas Pmm2 is only weakly expressed in this tissue. (C) 2001 E lsevier Science B.V. All rights reserved.