BHMT: Betaine-Homocysteine S-Methyltransferase
Key enzyme in homocysteine metabolism and one-carbon metabolism
Gene Information Card
| Symbol | BHMT |
|---|---|
| Full Name | Betaine-Homocysteine S-Methyltransferase |
| Gene Type | protein-coding |
| Chromosomal Location | 5q14.1 |
| NCBI Gene ID | 635 ncbi.nlm.nih.gov/gene/635 |
| Ensembl ID | ENSG00000145675 |
| UniProt ID | Q93088 |
| OMIM ID | 602888 |
| HGNC ID | 1047 |
| Aliases | BHMT1 |
Description
The BHMT gene encodes betaine-homocysteine S-methyltransferase, a zinc-dependent methyltransferase that catalyzes the transfer of a methyl group from betaine to homocysteine, producing methionine and dimethylglycine. This enzyme plays a critical role in homocysteine metabolism and the one-carbon metabolic pathway, primarily in the liver and kidney. BHMT is essential for maintaining cellular methylation balance and is implicated in homocystinuria, cardiovascular disease, and neural tube defects.
Disease Associations
| Disease category | Pathophysiological mechanism | Genomic evidence |
|---|---|---|
| Homocystinuria due to BHMT deficiency | Loss of BHMT activity leads to elevated homocysteine and reduced methionine synthesis | OMIM #602888; ClinVar |
| Cardiovascular disease | Elevated homocysteine (hyperhomocysteinemia) due to BHMT dysfunction contributes to vascular damage | NCBI Gene; PubMed |
| Neural tube defects | Maternal BHMT polymorphisms and altered homocysteine metabolism increase risk | OMIM; PubMed |
Expression Profile
Tissue Expression
| Tissue | nTPM | level |
|---|---|---|
| Liver | 58.2 | High |
| Kidney | 22.1 | Medium |
| Pancreas | 1.8 | Low |
| Small intestine | 0.9 | Low |
| Brain | 0.2 | Not detected |
Cell Line Expression
| Cell Line | nTPM | Notes |
|---|---|---|
| HepG2 (liver) | 45.3 | High expression |
| HEK293 (embryonic kidney) | 12.7 | Moderate expression |
| A549 (lung) | 0.5 | Low expression |
| K562 (leukemia) | 0.1 | Not detected |
Data source：Human Protein Atlas（proteinatlas.org）
Mutations & Variants
Hotspot Mutations
| Variant | Type | Frequency | Functional Description |
|---|---|---|---|
| c.716G>A (p.Arg239Gln) | Missense | <0.01% | Reduced enzyme activity; associated with hyperhomocysteinemia |
| c.1210C>T (p.Arg404Cys) | Missense | <0.01% | Impaired substrate binding; linked to homocystinuria |
| c.1A>G (p.Met1Val) | Start loss | <0.01% | Loss of protein expression; pathogenic |
Mutation functional classification
Loss of Function (LOF)
Missense and start-loss mutations reduce or abolish BHMT enzymatic activity, leading to elevated homocysteine and methionine deficiency.
Gain of Function (GOF)
No gain-of-function mutations reported in BHMT.
Dominant Negative (DN)
No dominant-negative mutations reported; BHMT functions as a homotetramer, but dominant-negative effects are not documented.
View complete mutation data：
Gene Ontology (GO)
| • betaine-homocysteine S-methyltransferase activity (GO:0008898) | • methionine biosynthetic process (GO:0009086) |
| • cytoplasm (GO:0005737) | • cytosol (GO:0005829) |
| • cellular amino acid biosynthetic process (GO:0008652) | • methionine salvage (GO:0009085) |
Pathways
• Homocysteine metabolism (Reactome: R-HSA-1614603)
• One-carbon metabolism (KEGG: hsa00670)
• Methionine salvage pathway (KEGG: hsa00270)
Protein Summary
BHMT is a 406-amino acid zinc-binding enzyme that forms a homotetramer. It catalyzes the conversion of homocysteine to methionine using betaine as a methyl donor. The protein is highly expressed in liver and kidney, with lower levels in other tissues. Structural studies show a TIM barrel fold with a zinc ion coordinated by three cysteine residues and one histidine. BHMT activity is regulated by substrate availability and is crucial for maintaining low homocysteine levels and adequate methionine for methylation reactions.
Related Services
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| BHMT Knockout HEK293 Cell Line | EDJ-KQ953 | Human | 635 | Details Get a Quote |
| BHMT2 Knockout HEK293 Cell Line | EDJ-KQ8129 | Human | 23743 | Details Get a Quote |
| BHMT Knockout HeLa Cell Line | EDJ-KQ52719 | Human | 635 | Details Get a Quote |
| BHMT2 Knockout HeLa Cell Line | EDJ-KQ55800 | Human | 23743 | Details Get a Quote |
| BHMT Knockout A-549 Cell Line | EDJ-KQ61191 | Human | 635 | Details Get a Quote |
| BHMT2 Knockout A-549 Cell Line | EDJ-KQ64296 | Human | 23743 | Details Get a Quote |
| BHMT Knockout HCT 116 Cell Line | EDJ-KQ69683 | Human | 635 | Details Get a Quote |
| BHMT2 Knockout HCT 116 Cell Line | EDJ-KQ72745 | Human | 23743 | Details Get a Quote |
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