MPI (Mannose Phosphate Isomerase) Gene
Key enzyme in N-glycosylation and congenital disorder of glycosylation type Ib
Gene Information Card
| Symbol | MPI |
|---|---|
| Full Name | Mannose Phosphate Isomerase |
| Gene Type | Protein coding |
| Chromosomal Location | 15q24.1 |
| NCBI Gene ID | 4351 ncbi.nlm.nih.gov/gene/4351 |
| Ensembl ID | ENSG00000178802 |
| UniProt ID | P34949 |
| OMIM ID | 154550 |
| HGNC ID | 7216 |
| Aliases | PMI, MGC111102, MGC111103 |
Description
The MPI gene encodes mannose phosphate isomerase (EC 5.3.1.8), a cytosolic enzyme that catalyzes the reversible interconversion of fructose-6-phosphate and mannose-6-phosphate. This reaction is essential for the synthesis of GDP-mannose, a key substrate for N-glycosylation and glycoprotein biosynthesis. Mutations in MPI cause congenital disorder of glycosylation type Ib (CDG-Ib), also known as MPI-CDG, characterized by hypoglycemia, protein-losing enteropathy, and hepatic fibrosis.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Congenital disorder of glycosylation type Ib (MPI-CDG) | Deficiency of mannose phosphate isomerase leads to impaired GDP-mannose synthesis and defective N-glycosylation; mannose supplementation can bypass the block. | ClinVar, OMIM |
| Hyperinsulinemic hypoglycemia | Disrupted glycosylation of ion channels or receptors may alter insulin secretion; observed in some MPI-CDG patients. | OMIM, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.3 | Medium |
| Small intestine | 8.7 | Medium |
| Kidney | 6.5 | Low |
| Pancreas | 5.9 | Low |
| Spleen | 4.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 14.1 | Hepatocellular carcinoma cell line |
| Caco-2 | 9.8 | Colorectal adenocarcinoma cell line |
| HEK 293 | 7.3 | Embryonic kidney cell line |
| K-562 | 3.5 | Chronic myelogenous leukemia cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.166G>A (p.Gly56Arg) | Missense | Common | Reduced enzyme activity; associated with CDG-Ib |
| c.1139C>T (p.Thr380Met) | Missense | Rare | Impaired protein stability; loss of function |
| c.448C>T (p.Arg150*) | Nonsense | Rare | Premature truncation; complete loss of function |
Mutation functional classification
Loss of Function (LOF)
Most MPI mutations result in loss of enzymatic activity, leading to MPI-CDG.
Gain of Function (GOF)
No gain-of-function mutations reported.
Dominant Negative (DN)
No dominant-negative effects described; disease is autosomal recessive.
View complete mutation data：
Gene Ontology (GO)
| • mannose-6-phosphate isomerase activity | • isomerase activity |
| • carbohydrate metabolic process | • GDP-mannose biosynthetic process |
| • protein N-linked glycosylation |
Pathways
• Fructose and mannose metabolism (KEGG: hsa00051)
• N-Glycan biosynthesis (KEGG: hsa00510)
• Metabolic pathways (KEGG: hsa01100)
Protein Summary
Mannose phosphate isomerase (PMI) is a 423-amino acid cytosolic enzyme that converts fructose-6-phosphate to mannose-6-phosphate. It is a homodimer with each subunit containing a zinc-binding site essential for catalysis. The enzyme is critical for the production of GDP-mannose, which is required for dolichol-linked oligosaccharide assembly in the endoplasmic reticulum. Deficiency leads to accumulation of fructose-6-phosphate and reduced mannose-6-phosphate, impairing N-glycosylation.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| MPI Knockout HEK293 Cell Line | EDJ-KQ5234 | Human | 4351 | Details Get a Quote |
| MPIG6B Knockout HEK293 Cell Line | EDJ-KQ9564 | Human | 80739 | Details Get a Quote |
| MPI Knockout A-549 Cell Line | EDJ-KQ28259 | Human | 4351 | Details Get a Quote |
| MPI Knockout HCT 116 Cell Line | EDJ-KQ28260 | Human | 4351 | Details Get a Quote |
| MPI Knockout HeLa Cell Line | EDJ-KQ28261 | Human | 4351 | Details Get a Quote |
| MPIG6B Knockout HeLa Cell Line | EDJ-KQ57340 | Human | 80739 | Details Get a Quote |
| MPIG6B Knockout A-549 Cell Line | EDJ-KQ65846 | Human | 80739 | Details Get a Quote |
| MPIG6B Knockout HCT 116 Cell Line | EDJ-KQ74270 | Human | 80739 | Details Get a Quote |
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