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Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The yeast CIT1 (mitochondrial citrate synthase) gene is subject to glucose repression and is further repressed by glucose plus glutamate. Based on deletion analysis of a CIT1-lacZ gene fusion, DNA sequences between -548 and -273 are required for full expression of CIT1. The region of transcription initiation and the putative TATA element are located at -150 to -100 and -195 respectively. A restriction fragment containing DNA sequences between -457 and -211 conferred activation and glucose-glutamate regulation when placed in either orientation upstream of a UAS-less heterologous yeast gene. Deletion of DNA sequences between -291 and -273 specifically eliminated derepression of CIT1, and destroyed one of two closely-spaced, potential binding sites for the HAP2,3,4 transcriptional activator protein. Ten-base-pair block substitutions in the region -367 to -348 reduced glucose-repressed expression. Thus, it appears that distinct DNA sequences upstream of CIT1 activate expression in glucose-repressed and derepressed cells. Possible mechanisms of regulation by glutamate plus glucose, are discussed.
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PMID:Distinct upstream activation regions for glucose-repressed and derepressed expression of the yeast citrate synthase gene CIT1. 792 3

The yeast nuclear gene CIT1 encodes mitochondrial citrate synthase, which catalyses the first and rate-limiting step of the tricarboxylic acid (TCA) cycle. Transcription of CIT1 is subject to glucose repression. Mutations in HAP2, HAP3 or HAP4 block derepression of a CIT1-lacZ gene fusion. The HAP2,3,4 transcriptional activator also activates nuclear genes encoding components of the mitochondrial electron transport chain, and thus it co-ordinates derepression of two major mitochondrial functions. Two DNA sequences resembling the consensus HAP2,3,4-binding site (ACCAATNA) are located at approximately -310 and -290, upstream of the CIT1 coding sequence. Deletion and mutation analysis indicates that the -290 element is critical for activation by HAP2,3,4. Glucose-repressed expression of CIT1 is largely independent of HAP2,3,4, is repressed by glutamate, and requires a DNA sequence between -367 and -348. Evidence is presented for a second HAP2,3,4-independent activation element located just upstream and overlapping the -290 HAP2,3,4 element.
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PMID:The HAP2,3,4 transcriptional activator is required for derepression of the yeast citrate synthase gene, CIT1. 798 86

Two metabolic pathways of the white adipocytes (i.e. de novo lipogenesis and lipolysis) require mitochondria functionality. In this report, the oxidative capacity of two white adipose tissues of rat and their respective isolated adipocytes were evaluated. Two major white fat pads, namely inguinal and epididymal tissues, were chosen as subcutaneous and visceral adipose tissues, respectively. The mitochondrial content of these tissues was estimated using cytological and biochemical analysis. Electron microscopy analysis showed higher mitochondrial density in epididymal than in inguinal adipocytes. The mitochondrial DNA content and mitochondrial enzymatic equipment were also higher in the former than in the latter tissue. A positive correlation between two mitochondrial enzymatic activities, namely cytochrome c oxidase and citrate synthase, and the mtDNA content of adipose tissue was reported. Moreover, NRF1 protein, which belongs to the transcriptional activator family and is thought to be involved in mitochondrial biogenesis regulation, was present in higher proportions in nuclei isolated from epididymal cells than in those from inguinal cells. Finally, greater abundance of mitochondria in epididymal tissue is in agreement with higher cytochrome c oxidase activity as well as increased respiration (i.e. basal and noradrenaline-stimulated) of adipocytes isolated from epididymal tissue as compared to adipocytes isolated from inguinal tissue. Therefore, white adipose tissue appears as a heterogeneous organ with marked variation in mitochondrial content depending on its anatomical location.
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PMID:Regional differences in oxidative capacity of rat white adipose tissue are linked to the mitochondrial content of mature adipocytes. 1566 97