Mitochondrial targeting signal-induced conformational change and repression of the peroxisomal targeting signal of the precursor for rat liver serine:pyruvate/alanine:glyoxylate aminotransferase.
In the rat liver, two mRNAs for serine:pyruvate (or alanine:glyoxylate) aminotransferase are generated from a single gene by alternative transcription initiation. The longer mRNA encodes a precursor of a mitochondrial enzyme that has a mitochondrial targeting signal at the N-terminus and is translocated into mitochondria. The shorter mRNA encodes a peroxisomal enzyme of mature size that is imported into peroxisomes. We have been interested in the mechanism of selective targeting to mitochondria of the precursor protein that also contains a peroxisomal targeting signal in the molecule. In this study, we examined the effect of the mitochondrial targeting signal on the conformation of the protein and on the function of the peroxisomal targeting signal in the precursor molecule. The results suggest that the mitochondrial targeting signal causes the conformation of the protein to become unfolded and that this conformational change in turn causes repression of the putative peroxisomal targeting signal contained in the precursor protein.
Oda
T
T
Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Shizuoka 431-3192, Japan. odat129@hama-med.ac.jp
Uchida
C
C
Miura
S
S
D017398:Alternative Splicing / Q000235:genetics*; D000818:Animals; D019286:Endopeptidase K; D004790:Enzyme Induction; D004926:Escherichia coli; D008930:Mitochondria, Liver / Q000201:enzymology / Q000378:metabolism*; D009154:Mutation; D020675:Peroxisomes / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation; D017510:Protein Folding; D011498:Protein Precursors / Q000235:genetics* / Q000378:metabolism; D021382:Protein Sorting Signals / Q000378:metabolism; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000637:Transaminases / Q000235:genetics* / Q000378:metabolism
D011498:Protein Precursors; D021382:Protein Sorting Signals; D011993:Recombinant Fusion Proteins; D000637:Transaminases; C019635:Alanine-glyoxylate transaminase; C022638:serine-pyruvate aminotransferase; D019286:Endopeptidase K