Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The concentrations of sulfur-containing amino acids, taurine, cystathionine, methionine and cystine, as well as cystathionine beta-synthase and gamma-lyase activities in various tissues of Agkistrodon blomhoffi (mamushi) were measured. The concentration of taurine in examined tissues was greater than the concentration of other sulfur-containing amino acids. The concentration of cystathionine in various tissues was also much higher than those of methionine and cystine, but the concentration of cystathionine in the brain was lower than that of methionine. In all tissues examined in this study, cystathionine beta-synthase activity was much higher than that of cystathionine gamma-lyase. The ratios of cystathionine beta-synthase to gamma-lyase activities in various tissues were 5.6 to approximately 85.6. The concentration of sulfur-containing amino acids in muscle and skin divided into eight portions of the body were also determined. The concentrations of methionine and cystine in each portion of muscle and skin were almost the same, but the concentrations of taurine and cystathionine in each portion of the body were varied.
Physiol Chem Phys Med NMR 2000
PMID:Contents of sulfur amino acids, and cystathionine beta-synthase and gamma-lyase activities in various tissues from agkistroden blomhoffi (mamushi). 1097 44

Cysteine synthesis is catalyzed by serine acetyltransferase (SAT) and O-acetylserine (thiol) lyase (OAS-TL) in the cytosol, plastids, and mitochondria of plants. Biochemical analyses of recombinant plant SAT and OAS-TL indicate that the reversible association of the proteins in the cysteine synthase complex (CSC) controls cellular sulfur homeostasis. However, the relevance of CSC formation in each compartment for flux control of cysteine synthesis remains controversial. Here, we demonstrate the interaction between mitochondrial SAT3 and OAS-TL C in planta by FRET and establish the role of the mitochondrial CSC in the regulation of cysteine synthesis. NMR spectroscopy of isolated mitochondria from WT, serat2;2, and oastl-C plants showed the SAT-dependent export of OAS. The presence of cysteine resulted in reduced OAS export in mitochondria of oastl-C mutants but not in WT mitochondria. This is in agreement with the stronger in vitro feedback inhibition of free SAT by cysteine compared with CSC-bound SAT and explains the high OAS export rate of WT mitochondria in the presence of cysteine. The predominant role of mitochondrial OAS synthesis was validated in planta by feeding [(3)H]serine to the WT and loss-of-function mutants for OAS-TLs in the cytosol, plastids, and mitochondria. On the basis of these results, we propose a new model in which the mitochondrial CSC acts as a sensor that regulates the level of SAT activity in response to sulfur supply and cysteine demand.
 ...
PMID:Mitochondrial cysteine synthase complex regulates O-acetylserine biosynthesis in plants. 2273 Mar 23