CBS

Cystathionine beta-synthase (CBS) is a PLP- and heme-containing enzyme (EC 4.2.1.22) that catalyzes the first and rate-limiting step of the transsulfuration pathway, condensing L-serine with L-homocysteine to form cystathionine. CBS is unique among PLP-dependent enzymes in also binding a b-type heme cofactor that functions as a redox sensor. The enzyme is allosterically activated by S-adenosyl-L-methionine (SAM) binding to its C-terminal regulatory domain containing tandem CBS (Bateman) motifs. CBS forms filamentous assemblies that are allosterically tunable by SAM. Alternative reactions can generate H2S through condensation of cysteine with homocysteine. CBS deficiency causes classical homocystinuria, characterized by hyperhomocysteinemia with multi-system manifestations including vascular, ocular, skeletal, and neurological complications.

Disorders

Relationship is the entry's genetic[].relationship_type. untyped means the entry has a genetic record for the gene but does not type it; its free-text association is shown instead.

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