CTH: Catalyzes the last step in the trans-sulfuration pathway from methionine to cysteine. Has broad substrate specificity. Converts cystathionine to cysteine, ammonia and 2-oxobutanoate. Converts two cysteine molecules to lanthionine and hydrogen sulfide. Can also accept homocysteine as substrate. Specificity depends on the levels of the endogenous substrates. Generates the endogenous signaling molecule hydrogen sulfide (H2S), and so contributes to the regulation of blood pressure. Acts as a cysteine-protein sulfhydrase by mediating sulfhydration of target proteins: sulfhydration consists of converting -SH groups into -SSH on specific cysteine residues of target proteins such as GAPDH, PTPN1 and NF-kappa-B subunit RELA, thereby regulating their function. Defects in CTH are the cause of cystathioninuria (CSTNU). It is an autosomal recessive phenotype characterized by abnormal accumulation of plasma cystathionine, leading to increased urinary excretion. Belongs to the trans-sulfuration enzymes family. 2 isoforms of the human protein are produced by alternative splicing.
Protein type: EC 4.4.1.1; Amino Acid Metabolism - cysteine and methionine; Cell cycle regulation; Other Amino Acids Metabolism - selenoamino acid; Energy Metabolism - nitrogen; Amino Acid Metabolism - glycine, serine and threonine; Lyase
Chromosomal Location of Human Ortholog: 1p31.1
Cellular Component: cytoplasm; cytosol; nucleus
Molecular Function: calmodulin binding; carbon-sulfur lyase activity; cystathionine gamma-lyase activity; homocysteine desulfhydrase activity; protein binding; pyridoxal phosphate binding
Biological Process: activation of NF-kappaB transcription factor; cysteine biosynthetic process; cysteine biosynthetic process via cystathionine; cysteine metabolic process; positive regulation of I-kappaB kinase/NF-kappaB cascade; protein homotetramerization; protein-pyridoxal-5-phosphate linkage via peptidyl-N6-pyridoxal phosphate-L-lysine; sulfur amino acid catabolic process; transsulfuration; unfolded protein response
Disease: Cystathioninuria
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