Summary of CBS
The CBS gene encodes an enzyme called cystathionine beta-synthase. It is responsible for using vitamin B6 to convert homocysteine and serine to a molecule called cystathionine. Another enzyme converts cystathionine to cysteine, which is used to build proteins or is broken down and excreted in urine (R).
Mutations in this gene can cause homocysteine and other potentially toxic compounds build up in the blood (R).
Also involved in the production of hydrogen sulfide, a gasotransmitter with signaling and protective effects on neurons.
Protein names
Recommended name:
Cystathionine beta-synthaseAlternative name(s):
Beta-thionaseSerine sulfhydrase
- RS1789953 (CBS) ??
- RS1801181 (CBS) ??
- RS2298758 (CBS) ??
- RS234706 (CBS) ??
- RS234709 (CBS) ??
- RS234714 (CBS) ??
- RS2851391 (CBS) ??
- RS4920037 (CBS) ??
- RS5742905 (CBS) ??
- RS6586282 (CBS) ??
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Top Gene-Substance Interactions
CBS Interacts with These Diseases
| Disease | Score |
Fixes
Substances That Increase CBS
| Substances | Interaction | Organism | Category |
Substances That Decrease CBS
| Substances | Interaction | Organism | Category |
Advanced Summary
Enzyme important in using vitamin B6 to convert several amino acids along a pathway (serine, homocysteine) into cystathionine [R]
Homocystinuria is an autosomal recessive disease that results from many SNPs in the CBS gene, the two most common being Ile278Thr and Gly307Ser [R]
Symptoms of homocystinuria include nearsightedness, risks of blood clotting, osteoporosis, dislocation at the front of the eye of the lens, and sometimes, developmental issues [R].
People who carry one SNP for homocystinuria are more easily deficient in B12 and folic acid [R].
CBS has been found to be increased in stroke victims, increasing the amount of hydrogen sulfide in the brain, which exacerbates stroke symptoms [R]
CBS tag-SNP rs11203172 is associated with a decreased risk for early-onset preeclampsia, a pregnancy complication marked by hypertension and proteinuria (protein in the urine). Women with SNP rs1789953 have increased levels of cysteine and cystathionine [R]
Higher levels of CBS have been found in colon cancer and hydrogen sulfide which is a byproduct of CBS, has been proven to increase tumor growth and proliferation [R]
More than 150 mutations that cause homocystinuria have been identified in the CBS gene.
Conditions with Increased Gene Activity
| Condition | Change (log2fold) | Comparison | Species | Experimental variables | Experiment name |
|---|
Conditions with Decreased Gene Activity
| Condition | Change (log2fold) | Comparison | Species | Experimental variables | Experiment name |
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Technical
The following transcription factors affect gene expression:
Tissue specificity:
In the adult strongly expressed in liver and pancreas, some expression in heart and brain, weak expression in lung and kidney. In the fetus, expressed in brain, liver and kidney.
Gene Pathways:
Caution:
There is a duplication of the CBS gene on chromosome 21. CBS, which was originally identified as the gene encoding cystathionine beta-synthase, and CBSL (AC P12345) encode identical proteins.
Enzyme Regulation:
Allosterically activated by S-adenosyl-methionine/AdoMet. Activated by S-adenosylhomocysteine/AdoHcy (PubMed:20506325). Binds non-covalently to a heme group that may control the redox sensitivity of the enzyme (PubMed:11483494, PubMed:12173932, PubMed:22738154).
Molecular Function:
- Cystathionine Beta-Synthase Activity
- Oxygen Binding
- Enzyme Binding
- Heme Binding
- Pyridoxal Phosphate Binding
- Ubiquitin Protein Ligase Binding
- Identical Protein Binding
- Protein Homodimerization Activity
- Metal Ion Binding
- Nitrite Reductase (No-Forming) Activity
- Carbon Monoxide Binding
- Nitric Oxide Binding
- Modified Amino Acid Binding
- S-Adenosyl-L-Methionine Binding
- Cysteine Synthase Activity
Biological Processes:
- Cysteine Biosynthetic Process From Serine
- L-Serine Metabolic Process
- L-Serine Catabolic Process
- Cellular Amino Acid Biosynthetic Process
- Cysteine Biosynthetic Process Via Cystathionine
- Cysteine Biosynthetic Process
- Transsulfuration
- L-Cysteine Catabolic Process
- Dna Protection
- Homocysteine Catabolic Process
- Homocysteine Metabolic Process
- Hydrogen Sulfide Biosynthetic Process
Drug Bank:
- L-Cysteine
- S-Adenosylmethionine
- L-Serine