ID:CBS_HUMAN DESCRIPTION: RecName: Full=Cystathionine beta-synthase; EC=4.2.1.22; AltName: Full=Beta-thionase; AltName: Full=Serine sulfhydrase; FUNCTION: Only known pyridoxal phosphate-dependent enzyme that contains heme. Important regulator of hydrogen sulfide, especially in the brain, utilizing cysteine instead of serine to catalyze the formation of hydrogen sulfide. Hydrogen sulfide is a gastratransmitter with signaling and cytoprotective effects such as acting as a neuromodulator in the brain to protect neurons against hypoxic injury (By similarity). CATALYTIC ACTIVITY: L-serine + L-homocysteine = L-cystathionine + H(2)O. COFACTOR: Pyridoxal phosphate. ENZYME REGULATION: Allosterically activated by adenosyl-methionine (AdoMet). PATHWAY: Amino-acid biosynthesis; L-cysteine biosynthesis; L- cysteine from L-homocysteine and L-serine: step 1/2. SUBUNIT: Homotetramer. SUBCELLULAR LOCATION: Cytoplasm. Nucleus. 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. DISEASE: Defects in CBS are the cause of cystathionine beta- synthase deficiency (CBSD) [MIM:236200]. CBSD is an enzymatic deficiency resulting in altered sulfur metabolism and homocystinuria. The clinical features of untreated homocystinuria due to CBS deficiency include myopia, ectopia lentis, mental retardation, skeletal anomalies resembling Marfan syndrome, and thromboembolic events. Light skin and hair can also be present. Biochemical features include increased urinary homocystine and methionine. SIMILARITY: Belongs to the cysteine synthase/cystathionine beta- synthase family. SIMILARITY: Contains 1 CBS domain. WEB RESOURCE: Name=CBS mutation database; URL="http://cbs.lf1.cuni.cz/index.php"; WEB RESOURCE: Name=GeneReviews; URL="http://www.ncbi.nlm.nih.gov/sites/GeneTests/lab/gene/CBS";
The RNAfold program from the Vienna RNA Package is used to perform the secondary structure predictions and folding calculations. The estimated folding energy is in kcal/mol. The more negative the energy, the more secondary structure the RNA is likely to have.
ModBase Predicted Comparative 3D Structure on P35520
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Orthologous Genes in Other Species
Orthologies between human, mouse, and rat are computed by taking the best BLASTP hit, and filtering out non-syntenic hits. For more distant species reciprocal-best BLASTP hits are used. Note that the absence of an ortholog in the table below may reflect incomplete annotations in the other species rather than a true absence of the orthologous gene.
Biological Process: GO:0006535 cysteine biosynthetic process from serine GO:0006563 L-serine metabolic process GO:0006565 L-serine catabolic process GO:0008152 metabolic process GO:0008652 cellular amino acid biosynthetic process GO:0019343 cysteine biosynthetic process via cystathionine GO:0019344 cysteine biosynthetic process GO:0019346 transsulfuration GO:0019448 L-cysteine catabolic process GO:0042262 DNA protection GO:0043418 homocysteine catabolic process GO:0050667 homocysteine metabolic process GO:0055114 oxidation-reduction process GO:0070814 hydrogen sulfide biosynthetic process
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Sequence and Links to Tools and Databases 
Common Gene Haplotype Alleles 
