Related Experiment Videos
Cloning and sequence analysis of mRNA for mouse aspartate aminotransferase isoenzymes
Abstract:
The nucleotide sequences of mRNAs for the mouse mitochondrial and cytosolic aspartate aminotransferase isoenzymes (mAspAT and cAspAT) (EC 2.6.1.1) were determined from complementary DNAs. The mAspAT mRNA comprises minimally 2460 nucleotides and codes for a polypeptide of 430 amino acid residues corresponding to the precursor form of the mAspAT (pre-mAspAT). The cAspAT mRNA comprises minimally 2086 nucleotides and codes for a polypeptide of 413 amino acid residues. The region coding for the mature mAspAT and that for the cAspAT show about 53% overall homology. The former shares 49% and the latter 48% of homology, respectively, with that of the Escherichia coli aspC gene, which has been shown to code for the E. coli AspAT (Kuramitsu, S., Okuno, S., Ogawa, T., Ogawa, H., and Kagamiyama, H. (1985) J. Biochem. (Tokyo) 97, 1259-1262). When the deduced amino acid sequence of the mouse pre-mAspAT was compared with that of the pig pre-mAspAT polypeptide, we found that they share a 94% homology and that the mouse pre-mAspAT yields a presequence consisting of 29 amino acid residues and a mature mAspAT, consisting of 401 amino acid residues. These numbers and the amino acid residues present at the putative cleavage site are all in complete agreement in these two species. The deduced amino acid sequence of the mouse cAspAT shares 91% homology with that of the pig cAspAT. Comparisons of the nucleotide and deduced amino acid sequences between the mouse and E. coli AspATs suggest that the mammalian mAspAT gene is more closely related to the E. coli aspC gene than is the mammalian cAspAT gene.
Insights
Mice aspartate aminotransferase (AspAT) mRNA sequences reveal distinct mitochondrial (mAspAT) and cytosolic (cAspAT) forms. Mammalian mAspAT shows closer evolutionary relation to E. coli aspC than cAspAT.
Area of Science:
- Biochemistry
- Molecular Biology
- Genetics
Background:
- Aspartate aminotransferase (AspAT) is a key enzyme in amino acid metabolism, existing as distinct mitochondrial (mAspAT) and cytosolic (cAspAT) isoenzymes.
- Understanding the genetic and molecular basis of these isoenzymes is crucial for comprehending cellular metabolic regulation and evolutionary relationships.
Purpose of the Study:
- To determine and analyze the nucleotide sequences of mouse mitochondrial and cytosolic aspartate aminotransferase (mAspAT and cAspAT) mRNAs.
- To compare the homology of mouse AspAT isoenzymes with their mammalian and bacterial counterparts.
Main Methods:
- Complementary DNA (cDNA) sequencing was employed to determine the nucleotide sequences of mAspAT and cAspAT mRNAs.
- Bioinformatic analysis was used to deduce amino acid sequences and compare homology between mouse, pig, and E. coli AspATs.
Main Results:
- Mouse mAspAT mRNA (2460 nucleotides) codes for a precursor of 430 amino acids, while cAspAT mRNA (2086 nucleotides) codes for 413 amino acids.
- Mature mAspAT and cAspAT regions share 53% homology. Mouse mAspAT shows 49% homology to E. coli AspAT, and cAspAT shows 48% homology.
- Mouse and pig pre-mAspAT share 94% amino acid homology, with identical presequence lengths (29 residues) and mature forms (401 residues). Mouse and pig cAspAT share 91% homology.
Conclusions:
- Mammalian mAspAT is evolutionarily more closely related to the E. coli aspC gene than is mammalian cAspAT.
- The high homology between mouse and pig AspAT isoenzymes suggests conserved functional and structural roles across mammalian species.