Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:1.3.5.1 (succinate dehydrogenase)
 8,177 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Phosphorylation of chloroplast thylakoid proteins, in particular light harvesting complex II (LHC II), is believed to play an important role in regulating photosynthetic electron transfer. Evidence supporting the involvement of multiple protein kinases in this system is mounting. We have re-examined pea thylakoid membranes and found evidence for a membrane-associated protein tyrosine kinase (PTK). Phosphorylation of many thylakoid proteins, including LHC II, is sensitive to treatment with the tyrosine kinase inhibitor genistein. Anti-phosphotyrosine antibodies react specifically with nine thylakoid proteins, two of which have been identified as components of LHC II. The phosphate associated with these two proteins is also resistant to strong base and acid treatment, further substantiating the assignment of phosphotyrosine. Potential interactions between this novel chloroplast PTK activity and the well-documented threonine kinase activities are discussed and the presence of a cascade of thylakoid protein kinases is proposed.
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PMID:A protein tyrosine kinase of chloroplast thylakoid membranes phosphorylates light harvesting complex II proteins. 978 95

Redox dependent protein phosphorylation in chloroplast thylakoids regulates distribution of excitation energy between the two photosystems of photosynthesis, PS I and PS II. Several thylakoid phosphoproteins are known to be phosphorylated on N-terminal threonine residues exposed to the chloroplast stroma. Phosphorylation of light harvesting complex II (LHC II) on Thr-6 is thought to account for redistribution of light energy from PS II to PS I during the transition to light state 2. Here, we present evidence that a protein tyrosine kinase activity is required for the transition to light state 2. With an immunological approach using antibodies directed specifically towards either phospho-tyrosine or phospho-threonine, we observed that LHC II became phosphorylated on both tyrosine and threonine residues. The specific protein tyrosine kinase inhibitor genistein, at concentrations causing no direct effect on threonine kinase activity, was found to prevent tyrosine phosphorylation of LHC II, the transition to light state 2, and associated threonine phosphorylation of LHC II. Possible reasons for an involvement of tyrosine phosphorylation in light state transitions are proposed and discussed.
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PMID:Protein tyrosine phosphorylation in the transition to light state 2 of chloroplast thylakoids. 1622 30

Gastrointestinal stromal tumors (GISTs) may be caused by germline mutations of the KIT and platelet-derived growth factor receptor-alpha (PDGFRA) genes and treated by Imatinib mesylate (STI571) or other protein tyrosine kinase inhibitors. However, not all GISTs harbor these genetic defects and several do not respond to STI571 suggesting that other molecular mechanisms may be implicated in GIST pathogenesis. In a subset of patients with GISTs, the lesions are associated with paragangliomas; the condition is familial and transmitted as an autosomal-dominant trait. We investigated 11 patients with the dyad of 'paraganglioma and gastric stromal sarcoma'; in eight (from seven unrelated families), the GISTs were caused by germline mutations of the genes encoding subunits B, C, or D (the SDHB, SDHC and SDHD genes, respectively). In this report, we present the molecular effects of these mutations on these genes and the clinical information on the patients. We conclude that succinate dehydrogenase deficiency may be the cause of a subgroup of GISTs and this offers a therapeutic target for GISTs that may not respond to STI571 and its analogs.
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PMID:Clinical and molecular genetics of patients with the Carney-Stratakis syndrome and germline mutations of the genes coding for the succinate dehydrogenase subunits SDHB, SDHC, and SDHD. 1766 67