Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.24.11 (CD10)
 9,792 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Ornithine transcarbamoylase (OTC) is inactivated by liver lysosomes. Carbamoyl phosphate prevents the inactivation of OTC by lysosomes, while ATP, ADP, GTP, GDP 1,N6-ethenoadenosine 5'-triphosphate and particularly epsilon-ATP stimulate it. Both stimulation and protection occur at concentrations within the physiological range of ATP and carbamoyl phosphate. Inactivation of OTC is followed by extensive proteolysis. Since the inactivation is prevented by leupeptin, antipain and L-(tosylamido-2-phenyl)ethylchloromethyl ketone, the proteolytic susceptibility of OTC to lysosomes could be due to thiol endopeptidase(s). 1,N6-Ethenoadenosine 5'-triphosphate also markedly increases OTC susceptibility to trypsin and elastase. ATP analogs had no stimulatory effect on OTC inactivation by lysosomes; none of the inhibitors of ATPases tested inhibited the ATP effect. The ATP stimulation does not require Mg2+. These findings indicate a new role for ATP, GTP and related nucleotides in protein breakdown. The ATP, ADP, GTP, GDP stimulation, together with the carbamoyl protection of OTC, agree well with the molecular plasticity hypothesis model.
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PMID:Purine nucleotides stimulate while carbamoyl phosphate protects inactivation of ornithine transcarbamoylase by disrupted lysosomes. 399 99

To investigate the molecular mechanism of chloroplast biogenesis and development, we characterized an Arabidopsis mutant (dg169, delayed greening 169) which showed growth retardation and delayed greening phenotype in leaves. Newly emerged chlorotic leaves recovered gradually with leaf development in the mutant, and the mature leaves showed similar phenotype to those of wild-typewild-type plants. Compared with wild-type, the chloroplasts were oval-shaped and smaller and the thylakoid membranes were less abundant in yellow section of young leaves of dg169. In addition, the functions of photosystem II (PSII) and photosystem I (PSI) were also impaired. Furthermore, the amount of core subunits of PSII and PSI, as well as PSII and PSI complexes reduced in yellow section of young leaves of dg169. Map-based positional cloning identified that phenotype of dg169 was attributed to a point mutation of ATase2 which converts the conserved Ile-155 residue to Asn. ATase2 catalyzes the first step of de novo purine biosynthesis. This mutation resulted in impaired purine synthesis and a significant decrease in ATP, ADP, GTP and GDP contents. The analysis of ATase2-GFP protein fusion showed that ATase2 was localized to nucleoid of chloroplasts. Our results further demonstrated that the levels of PEP-dependent transcripts in yellow section of young leaves of dg169 were decreased while NEP-dependent and both PEP- and NEP-dependent transcripts and chloroplast DNA replications were increased. The results in this study suggest that ATase2 plays an essential role in early chloroplast development through maintaining PEP function.
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PMID:Purine biosynthetic enzyme ATase2 is involved in the regulation of early chloroplast development and chloroplast gene expression in Arabidopsis. 2583 56