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Ornithine transcarbamylase deficiency: a case with a truncated enzyme precursor and a case with undetectable mRNA activity
Author(s) -
Kodama H.,
Ohtake A.,
Mori M.,
Okabe I.,
Tatibana M.,
Kamoshita S.
Publication year - 1986
Publication title -
journal of inherited metabolic disease
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.462
H-Index - 102
eISSN - 1573-2665
pISSN - 0141-8955
DOI - 10.1007/bf01799456
Subject(s) - ornithine transcarbamylase , ornithine carbamoyltransferase , messenger rna , enzyme , in vitro , mitochondrion , biology , microbiology and biotechnology , gene product , ornithine , medicine , incubation , endocrinology , biochemistry , gene expression , urea cycle , gene , amino acid , arginine
The cell‐free translation of ornithine transcarbamylase (OTC) mRNA from the livers of two heterozygous patients (from different families) with OTC deficiency was performed. The enzyme activities and the immunoreactive proteins in both patients were about 5% of those in controls. Immunoblotting assay of liver extracts from both patients showed decreased amounts of the OTC protein. The mRNA from the liver of patient 1 directed the synthesis of a very small amount of OTC precursor of normal subunit size (40 000 Da), whereas that from patient 2 directed the synthesis of small amounts of two distinct in vitro products; one was 40 000 Da and the other was about 30 000 Da. The in vitro product of normal precursor synthesized with mRNA from patient 2 was converted to mature‐sized OTC by isolated rat liver mitochondria, whereas the smaller product was degraded during the incubation with the mitochondria. These results indicate that in both patients the translatable level of mRNA for active OTC from liver cells was much lower than that in the controls. The results also suggest that in patient 2, the smaller product presumably derived from an abnormal gene could not be transferred to the mitochondria.