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An Integrated Approach for Microprotein Identification and Sequence Analysis
Published on: July 12, 2022
Identification and localization of two mouse phosphomannomutase genes, Pmm1 and Pmm2
L Heykants1, E Schollen, S Grünewald
1Center for Human Genetics, University of Leuven, U.Z. Gasthuisberg O&N6, Herestraat 49, B-3000, Leuven, Belgium.
Abstract:
Phosphomannomutases catalyze the reversible conversion of mannose 6-phosphate 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 genes, Pmm1 and Pmm2. The chromosomal localization of the two mouse genes has been determined. We also present the gene structure and the exon-intron organization of Pmm1 and Pmm2. Pmm1 maps to mouse chromosome 15, Pmm2 to chromosome 16. These chromosomal regions are syntenic with regions on human chromosomes 22 and 16, respectively. The Pmm1 gene is composed of eight exons and spans approximately 9.5 kb. The genomic structure is extremely well conserved between the human and mouse gene. The Pmm2 gene consists of eight exons and spans a larger genomic region ( approximately 20 kb). An alignment of the human and mouse protein sequences confirms the conservation among this family of phosphomannomutases. The two mouse genes are expressed in many tissues, but the expression pattern is slightly different between Pmm1 and Pmm2. The most striking difference is the high expression of Pmm1 in brain tissue, whereas Pmm2 is only weakly expressed in this tissue.
Insights
Researchers characterized mouse phosphomannomutase genes (Pmm1 and Pmm2), finding conserved structures and varied expression patterns, particularly high Pmm1 expression in brain tissue. This aids understanding of congenital disorders of glycosylation.
Area of Science:
- Biochemistry
- Genetics
- Molecular Biology
Background:
- Phosphomannomutases (PMMs) are enzymes crucial for carbohydrate metabolism, converting mannose 6-phosphate to mannose 1-phosphate.
- Human PMM1 and PMM2 isozymes have been identified, with mutations in PMM2 linked to congenital disorders of glycosylation type Ia (CDG-Ia).
Purpose of the Study:
- To characterize the mouse orthologous genes, Pmm1 and Pmm2, including their chromosomal localization, gene structure, and expression patterns.
- To compare the genomic organization and protein sequence conservation between human and mouse PMM genes.
Main Methods:
- Determining chromosomal localization of Pmm1 and Pmm2 in mice.
- Analyzing gene structure, including exon-intron organization.
- Aligning human and mouse protein sequences.
- Assessing tissue-specific gene expression patterns.
Main Results:
- Pmm1 maps to mouse chromosome 15, and Pmm2 maps to mouse chromosome 16, regions syntenic to human chromosomes 22 and 16, respectively.
- Both Pmm1 and Pmm2 genes consist of eight exons, with conserved genomic structures between human and mouse orthologs.
- Mouse PMM protein sequences show significant conservation with human counterparts.
- Differential expression observed, with Pmm1 highly expressed in brain tissue and Pmm2 weakly expressed.
Conclusions:
- The mouse Pmm1 and Pmm2 genes are well-conserved in genomic structure and protein sequence compared to their human orthologs.
- Distinct tissue expression patterns, especially the high Pmm1 brain expression, suggest specialized roles for these isozymes in mice.
- These findings provide a foundation for further research into PMM function and the pathogenesis of CDG-Ia in a mammalian model.
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