CBS: 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. Defects in CBS are the cause of cystathionine beta- synthase deficiency (CBSD). 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. Belongs to the cysteine synthase/cystathionine beta- synthase family. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: Other Amino Acids Metabolism - selenoamino acid; Amino Acid Metabolism - cysteine and methionine; EC 4.2.1.22; Lyase; Amino Acid Metabolism - glycine, serine and threonine
Cellular Component: cytoplasm; cytosol; nucleus
Molecular Function: cystathionine beta-synthase activity; cysteine synthase activity; enzyme binding; heme binding; identical protein binding; lyase activity; metal ion binding; nitrite reductase (NO-forming) activity; oxygen binding; protein homodimerization activity; pyridoxal phosphate binding; ubiquitin protein ligase binding
Biological Process: amino acid biosynthetic process; blood vessel remodeling; cerebellum morphogenesis; cysteine biosynthetic process; cysteine biosynthetic process from serine; cysteine biosynthetic process via cystathionine; endochondral ossification; homocysteine metabolic process; maternal process involved in pregnancy; negative regulation of apoptosis; regulation of blood vessel size; regulation of cGMP metabolic process; regulation of JNK activity; response to folic acid; superoxide metabolic process; transsulfuration
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