cDNA clones for rat cytosolic aspartate aminotransferase (cAspAT, L-aspartate:2-oxoglutarate aminotransferase) [EC 2.6.1.1] were isolated from a rat cDNA library, and the primary structure of the gene for cAspAT was deduced from its cDNA sequence. Rat cAspAT consists of 412 amino acids and its molecular weight is 46,295. The deduced amino acid sequence of rat cAspAT was compared with the sequences of AspATs from other species. The degree of sequence identities of rat/mouse cAspAT, rat/pig cAspAT, rat/chicken cAspAT, rat/pig mAspAT, and rat/Escherichia coli AspAT were 97.1, 89.6, 81.7, 48.1, and 41.2%, respectively. A coding region of rat cAspAT cDNA was inserted into E. coli expression vector pUC9, and enzymatically active cAspAT was expressed as a beta-galactosidase-cAspAT hybrid protein. This hybrid protein represented about 18% of the soluble proteins in E. coli and its kinetic properties were comparable with those of cAspAT preparations purified from rat liver.

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An unusual pheochromocytoma was incidentally discovered in a 48-year-old woman. The patient had a 3-year history of myasthenia gravis. At the time of examination in our hospital, the right adrenal tumor was incidentally discovered by ultrasonography of the abdomen. She had no history of headache, perspiration, palpitation or hypertension. Although blood catecholamine levels were within the normal limits, urinary secretion of catecholamine was elevated.Histologically, the tumor was diagnosed to be mixed ganglioneuroma/pheochromocytoma and histochemically confirmed to produce vasoactive intestinal polypeptide. Such a tumor is quite rare.