Cystathionine Beta Synthase (CbS)

Cystathionine Beta Synthase acts as a homotetramer to catalyze the conversion of homocysteine to cystathionine, the first step in the transsulfuration pathway. The encoded protein is allosterically activated by adenosyl-methionine and uses pyridoxal phosphate as a cofactor. Defects in this gene can cause cystathionine beta-synthase deficiency (CBSD), which can lead to homocystinuria. Multiple alternatively spliced transcript variants have been found for this gene.The deduced 551-residue protein showed about 90% identity with the rat protein. Northern blot analysis identified a major 2.7-kb mRNA transcript.The gene is expressed as a 2.5-kb mRNA species mostly in liver and pancreas, with faint expression in brain, heart, kidney and lung. In addition, a 3.7-kb transcript was found in pancreas and liver.