The level of β-alanine aminotransferase activity in regenerating and differentiating rat liver

Fujimoto, Shigeyoshi; Mizutani, Naomi; Mizota, Chizuru; Tamaki, Nanaya

doi:10.1016/0304-4165(86)90061-9

Cited by 24 publications

(13 citation statements)

References 16 publications

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“…Therefore, the mature‐GABA AT from pig [24,26] or human [25] was composed of the same 472 amino acid residues, while the mature one from rat [10] was 473. The N‐terminal amino acids of β‐AlaAT I from rat liver and GABA AT from rat brain are Val [6] and I1e [11], respectively. The N‐terminal of rat mature‐GABA AT may be further cleaved in the liver (Scheme 1).…”

Section: Discussionmentioning

confidence: 99%

“…The immunoblot analysis was conducted by the method of Towbin et al [13]. Rabbit polyclonal antibody against rat liver β‐AlaAT I has been previously prepared [6]. The densities of bands corresponding to mature‐GABA AT and mature‐β‐AlaAT I were determined using an image analyzer (Fujifilm FLA‐2000, Tokyo, Japan).…”

Section: Methodsmentioning

confidence: 99%

“…Rat liver β‐AlaAT I mRNA and rat brain GABA AT mRNA are transcripts from the same gene [10]. However, the N‐terminal amino acid of rat liver β‐AlaAT I is Val [6], while that of rat brain GABA AT has been identified as I1e [11] by the dansyl method. The amino acid sequence predicted from rat liver cDNA suggests that the precursor to β‐AlaAT I (pre‐GABA AT) consists of a liver‐type mature enzyme of 466 amino acid residues, with 34 residues attributed to the leader peptide.…”

Section: Introductionmentioning

confidence: 99%

“…β‐AlaAT I purified from rat liver also catalyzes the transamination of 4‐aminobutyrate (GABA) [6] and l ‐β‐aminoisobutyrate [7] in addition to β‐alanine, while β‐AlaAT II is not active for GABA [8]. It is well known that GABA is a major inhibitory transmitter in many invertebrate systems and also in the vertebrate central nervous system.…”

Section: Introductionmentioning

confidence: 99%

“…Enzyme activity of β‐AlaAT I is mainly distributed in the mitochondrial matrix of the brain [9], liver [4], and kidney [5] in rats. The immunological and kinetic properties show that β‐AlaAT I from rat liver closely resembles those of GABA aminotransferase (GABA AT) from the rat brain [6]. Rat liver β‐AlaAT I mRNA and rat brain GABA AT mRNA are transcripts from the same gene [10].…”

Section: Introductionmentioning

confidence: 99%

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Purification and expression of a processing protease on β‐alanine‐oxoglutarate aminotransferase from rat liver mitochondria

et al. 2004

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GABA[arrow beta]AlaAT convertase is an endopeptidase that processes brain-type 4-aminobutyrate aminotransferase (GABA AT; EC 2.6.1.19) to liver-type b-alanine-oxoglutarate aminotransferase (b-AlaAT I) in rats. Its molecular mass was 180 kDa as determined by gel filtration. A subunit molecular mass of 97 652 Da was measured using MALDI-TOF MS. The N-terminal sequence of the purified GABA[arrow beta]AlaAT convertase was SRVEVSKVLILGSGGLSIGQAGEFDYSGS-QAV-and was identical to residues 418-449 of carbamoylphosphate synthetase I (CPS I; EC 1.2.1.27) purified from rat liver. The subunit molecular mass and the N-terminal amino acid sequence suggested that GABA[arrow beta]AlaAT convertase was the 418-1305 peptide of CPS I. An expression vector containing the coding region of the 418-1305 peptide of rat CPS I was transfected into NIH3T3 cells and the extract of the cells showed GABA[arrow beta]AlaAT convertase activity.

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Purification and expression of a processing protease on β‐alanine‐oxoglutarate aminotransferase from rat liver mitochondria

et al. 2004

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Zonation of cholesterol and glycerolipid synthesis in regenerating rat livers

1993

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Hepatic zonation of cholesterol and glycerolipid synthesis was investigated in regenerating rat livers 24 hr after partial hepatectomy. Tritiated acetate and [U-14C]glycerol were injected into rats' peritoneal cavities for a short-term labeling study. Periportal and perivenous hepatocytes were isolated by digitonin collagenase perfusion. Cholesterol synthesis was significantly higher in periportal hepatocytes of the sham-operated livers (periportal/perivenous = 1.67; p < 0.05). Twenty-four hours after partial hepatectomy, cholesterol synthesis was selectively decreased by 40% (p < 0.01) in periportal hepatocytes. Consequently, hepatic zonation of cholesterol synthesis was abolished in regenerating livers. To study the cholesterol homeostasis on a long-term basis, we substituted deuterated water (25% enriched) for drinking water for 5 days to label newly synthesized cholesterol in a steady state. This procedure clearly demonstrated the net negative cholesterol balance 24 hr after partial hepatectomy. However, the newly synthesized cholesterol contributed equally to the cellular cholesterol pool in both zones. The synthesis of glycerolipids, whether measured from tritiated acetate or [U-14C]glycerol, was significantly increased without apparent zonation in the regenerating livers (twofold increase in phospholipid, and threefold to sevenfold increase in triacylglycerol). We concluded that hepatic zonation of cholesterol synthesis is caused by higher de novo synthesis in periportal hepatocytes, which is abolished in regenerating livers. No zonation of glycerolipid synthesis exists in normal and regenerating livers.

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