CMAS (Cytidine Monophosphate N-Acetylneuraminic Acid Synthetase)
Key enzyme in sialic acid biosynthesis and cellular glycosylation
Gene Information Card
| Symbol | CMAS |
|---|---|
| Full Name | Cytidine monophosphate N-acetylneuraminic acid synthetase |
| Gene Type | Protein coding |
| Chromosomal Location | 12p13.31 |
| NCBI Gene ID | 55907 ncbi.nlm.nih.gov/gene/55907 |
| Ensembl ID | ENSG00000111276 |
| UniProt ID | Q8NFW8 |
| OMIM ID | 603316 |
| HGNC ID | 18290 |
| Aliases | CMP-Neu5Ac synthetase, CSS, NANS2 |
Description
The CMAS gene encodes cytidine monophosphate N-acetylneuraminic acid synthetase, an enzyme that catalyzes the activation of N-acetylneuraminic acid (Neu5Ac) to CMP-Neu5Ac, a key step in sialic acid biosynthesis. Sialic acids are terminal sugars on glycoproteins and glycolipids, involved in cell-cell interactions, immune modulation, and pathogen binding. CMAS is essential for proper glycosylation and is expressed in various tissues.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Sialuria (French type) | Deficiency in CMAS leads to accumulation of free sialic acid in urine and tissues | OMIM #269921 |
| Congenital disorder of glycosylation type II (CMAS-related) | Impaired CMP-sialic acid synthesis disrupts protein glycosylation | ClinVar, PubMed |
| Cancer (various) | Altered sialylation via CMAS overexpression may promote tumor progression and metastasis | COSMIC, PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 12.5 | Medium |
| Brain | 8.3 | Medium |
| Kidney | 10.1 | Medium |
| Lung | 7.6 | Low |
| Heart | 6.2 | Low |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 | 14.2 | Hepatocellular carcinoma cell line |
| SH-SY5Y | 9.8 | Neuroblastoma cell line |
| A549 | 7.1 | Lung carcinoma cell line |
| HEK293 | 11.5 | Embryonic kidney cell line |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.1000C>T (p.Arg334Trp) | Missense | <0.01% | Reduced enzyme activity; associated with sialuria |
| c.124G>A (p.Gly42Ser) | Missense | <0.01% | Impaired CMP-Neu5Ac synthesis; reported in CDG |
| c.1465_1466del (p.Leu489fs) | Frameshift | <0.01% | Loss of function; likely pathogenic |
Mutation functional classification
Loss of Function (LOF)
Missense and frameshift mutations reduce or abolish CMAS enzymatic activity, leading to sialic acid deficiency and glycosylation defects.
Gain of Function (GOF)
Not reported.
Dominant Negative (DN)
Not reported.
View complete mutation data：
Gene Ontology (GO)
| • GO:0008781 - CMP-N-acetylneuraminate phosphodiesterase activity | • GO:0008782 - CMP-N-acetylneuraminate synthase activity |
| • GO:0005794 - Golgi apparatus | • GO:0006054 - N-acetylneuraminate metabolic process |
| • GO:0016051 - carbohydrate biosynthetic process |
Pathways
• Sialic acid metabolism (Reactome: R-HSA-4085001)
• Glycosylation of proteins (Reactome: R-HSA-975578)
Protein Summary
CMAS is a 433-amino acid protein localized to the Golgi apparatus. It catalyzes the formation of CMP-N-acetylneuraminic acid from CTP and N-acetylneuraminic acid, providing activated sialic acid for sialyltransferases. The enzyme is critical for the synthesis of sialylated glycoconjugates, which modulate cell adhesion, signaling, and immune recognition. Structural studies reveal a homodimeric organization with a conserved active site.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| CMAS Knockout HEK293 Cell Line | EDJ-KQ12958 | Human | 55907 | Details Get a Quote |
| CMAS Knockout A-549 Cell Line | EDJ-KQ42165 | Human | 55907 | Details Get a Quote |
| CMAS Knockout HCT 116 Cell Line | EDJ-KQ42166 | Human | 55907 | Details Get a Quote |
| CMAS Knockout HeLa Cell Line | EDJ-KQ42167 | Human | 55907 | Details Get a Quote |
| CMAS Knockout HAP1 Cell Line | EDC08187 | Human | 55907 | Details Get a Quote |
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