Abstract

The structural abnormality of mRNA for argininosuccinate synthetase (ASS) and the structure of immune cross-reactive material for ASS (ASS-CRM) in the liver of a patient with type III citrullinemia were analyzed using dot and Northern blot hybridization, S1 nuclease analysis, and a sensitive enzyme-linked immunosorbent assay. The patient's liver contained no detectable ASS activity, the ASS-CRM content was about 0.5% of that in the control and the ASS mRNA content was almost normal. The ASS mRNA of the case was found to have an apparent structural abnormality; approximately 1.57 kb in length caused by a defect of about 0.1 kb near the 3' end of the coding region. Furthermore, gel filtration analysis revealed that the ASS-CRM had a molecular weight indistinguishable from the control ASS. These results indicate that the abnormal mRNA of the patient was translated in vivo to an immune-cross-reactive protein that was able to form a quaternary structure.