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Query: UNIPROT:P01275 (glucagon)
 26,492 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The 7- to 10-fold increase in the rat liver serine:pyruvate aminotransferase activity after glucagon administration was shown to occur mainly in the mitochondrial matrix of parenchymal cells. The enzyme was purified from glucagon-treated rat liver mitochondria to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. A specific rabbit antibody was prepared against the purified enzyme. Upon Ouchterlony double diffusion analysis, the mitochondrial extracts of glucagon-treated rat liver produced a single and fused precipitin line between the purified enzyme against the antibody. The supernatant fraction of glucagon-treated rat liver and the mitochondrial extracts of normal liver were also shown to make a single and fused precipitin line with the purified enzyme, when applied in large quantities. The quantitative immunotitration demonstrated that the glucagon-induced increase in the activity of liver serine:pyruvate aminotransferase were accompanied by the parallel increase in the amount of the enzyme antigen. Isotopic leucine incorporation studies showed that the relative rate of synthesis of the enzyme was increased approximately 10-fold by glucagon administration under the conditions employed. The rate of the degradation of the aminotransferase in the normal rat liver was a relatively slow process with a half-life of approximately 30 h. Thus the accumulation of serine:pyruvate aminotransferase in rat liver mitochondria by glucagon treatment can be ascribed mainly to the rise in the rate of enzyme synthesis.
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PMID:Immunochemical studies on induction of rat liver mitochondrial serine: pyruvate aminotransferase by glucagon. 41 59

Studies were performed in the rat liver to examine whether or not insulin as well as glucagon causes the induction of mitochondrial serine:pyruvate aminotransferase (SPTm) [EC 2.6.1.51] and if so, whether the mechanisms of induction are similar or different for the two hormones. Not only glucagon but also insulin induced SPTm. Cell-free translation assaying and RNA blot analysis showed that both hormones cause an increase in the hepatic level of mRNA for the precursor of SPTm. Their effects were virtually additive, and the time course of the increase in the mRNA level differed between the hormones. The maximal increase induced by glucagon was observed 3.5 h after the hormone injection while that by insulin was found after 6 h. The increase in the mRNA due to insulin was completely inhibited by the co-administration of cycloheximide, while that due to glucagon was not. The finding suggests that a newly synthesized, insulin-dependent protein(s) is involved in the regulation of the mRNA level by insulin. On the other hand, hydrocortisone treatment selectively suppressed the increase in the mRNA due to glucagon. These data indicate that the synthesis of the mRNA for SPTm is regulated by glucagon and insulin through different mechanisms. The size of the hormone-induced mRNA for SPTm gradually decreased with time, but the cell-free translation products did not exhibit size alteration. RNase H digestion to remove the poly(A) tail of the mRNA indicated that shortening of the poly(A) sequence might be responsible for the time-dependent size alteration of the mRNA.
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PMID:Induction of mitochondrial serine:pyruvate aminotransferase of rat liver by glucagon and insulin through different mechanisms. 256 60

The subcellular distribution of asparagine:oxo-acid aminotransferase (EC 2.6.1.14) in rat liver was examined by centrifugation in a sucrose density gradient. About 30% of the homogenate activity after the removal of the nuclear fraction was recovered in the peroxisomes, about 56% in the mitochondria, and the remainder in the soluble fraction from broken peroxisomes. The mitochondrial asparagine aminotransferase had identical immunological properties with the peroxisomal one. Glucagon injection to rats resulted in the increase of its activity in the mitochondria but not in the peroxisomes. Immunological evidence was obtained that the enzyme was identical with alanine:glyoxylate aminotransferase 1 (EC 2.6.1.44) which had been reported to be identical with serine:pyruvate aminotransferase (EC 2.6.1.51) (Noguchi, T. (1987) in Peroxisomes in Biology and Medicine (Fahimi, H. D., and Sies, H., eds) pp. 234-243, Springer-Verlag, Heidelberg). The same results as described above were obtained with mouse liver. All of alanine:glyoxylate aminotransferase 1 in livers of mammals other than rodents, which cross-react with the antibody against rat liver alanine:glyoxylate aminotransferase 1, had no asparagine aminotransferase activity.
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PMID:Identification of mammalian aminotransferases utilizing glyoxylate or pyruvate as amino acceptor. Peroxisomal and mitochondrial asparagine aminotransferase. 312 7

Cloned cDNAs for rat liver serine: pyruvate aminotransferase were obtained by screening of a cDNA expression bank of rat liver with an antibody against the enzyme. Nineteen clones were isolated from 33 000 transformants and most of them had common fragments of cDNA on analysis by digestion with some restriction enzymes. These clones were identified as those containing cDNA for serine:pyruvate aminotransferase by the following criteria. (a) At the nucleic acid level, a 500-base-pair fragment of cDNA prepared by digestion of cDNAs with EcoRI and PstI hybridized with the mRNA coding for serine:pyruvate aminotransferase as judged by hybrid-selected and hybrid-arrested translations. (b) Specific proteins were detected in nine bacterial clones, a 40-kDa protein in one clone and a 39-kDa protein in eight clones. Among them only the 40-kDa protein was found to be solubilized from the cell by sonication, and this protein was immunoprecipitated with an antibody against serine:pyruvate aminotransferase of rat liver. (c) High activity of serine:pyruvate aminotransferase was expressed both in whole cell suspension and sonicated extract prepared from the transformant producing the 40-kDa protein, and 99% of the activity was immunoreactive with the antibody. Two types of mRNA for serine:pyruvate aminotransferase were detected on the RNA blot analysis by using cloned cDNA fragment as a probe. The larger mRNA (approximately 1600 nucleotides) was glucagon-inducible while the smaller one (approximately 1500 nucleotides) was not affected by the hormone.
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PMID:Cloning and expression in Escherichia coli of cDNA for serine: pyruvate aminotransferase of rat liver. 389 25

Processing and uptake of the precursor of serine: pyruvate aminotransferase [EC 2.6.1.51] by mitochondria were studied in vitro and in vivo. Serine: pyruvate aminotransferase was synthesized mainly on free ribosomes as judged by immunoprecipitation of puromycin-labeled nascent peptides prepared from free and bound ribosomes. The precursor of rat liver serine:pyruvate aminotransferase (pSPT) synthesized in vitro was post-translationally processed to an apparently mature form by isolated rat liver mitochondria. Available evidence indicated that the processed product was localized in the matrix of mitochondria. Mature serine:pyruvate aminotransferase did not inhibit the in vitro processing, suggesting that the extra peptide was necessary for the mitochondrial uptake of the precursor. In the livers of rats fed a vitamin B6-deficient high-protein diet, the induction by glucagon of serine:pyruvate aminotransferase occurred and most of the induced enzyme existed in mitochondria as the apo-form, suggesting that pSPT was taken up by mitochondria and processed in the apo-form under the conditions employed. In the in vitro system, on the other hand, the processing of pSPT proceeded both in the absence and presence of pyridoxal 5'-phosphate. Should the precursor also bind the prosthetic molecule, therefore, it would be transported into mitochondria in both the apo- and holo-forms. When isolated rat hepatocytes were labeled with [35S]methionine, labeled pSPT appeared in the cytosolic fraction and was transported rapidly into mitochondria in association with the processing. This uptake and processing were inhibited by a fluorescent laser dye, rhodamine 123, and the precursor accumulated in the cytosol in the presence of the dye.
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PMID:Uptake and processing of serine: pyruvate aminotransferase precursor by rat liver mitochondria in vitro and in vivo. 672 36

We have reported the isolation of genomic clones encoding serine:pyruvate aminotransferase (SPT; also named alanine:glyoxylate aminotransferase, AGT) (T. Oda, T. Funai, and A. Ichiyama, 1990, J. Biol. Chem. 265: 7513-7519). These clones contained the entire SPT/AGT gene of 10 kb. In this work, we characterized this gene. The SPT/AGT gene consists of 11 exons, and the exon-intron boundaries have typical splice donor and acceptor sequences. Determination of the nucleotide sequence up to -1.25 kb from the transcription initiation site revealed the presence of many putative cis elements, some of which may explain the transcriptional regulation of the SPT/AGT gene by glucagon and glucocorticoid. The nucleotide sequence around the 5' flanking region of the rat SPT/AGT gene and the whole gene organization were compared with those of the human SPT/AGT gene. No obvious similarities were observed in the 5' flanking region up to -1.25 kb from the initiation site of the gene, but exons 2 to 10 of the rat and human genes have identical sizes and show high similarities.
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PMID:Characterization and sequence analysis of rat serine:pyruvate/alanine:glyoxylate aminotransferase gene. 840 72