[Characterization of tyrosine aminotransferase by an immunoadsorption technic. Application to the measurement of the specific messenger RNA].

A specific antiserum was used in an enzyme-linked immunoadsorbent assay (ELISA) for tyrosine amino-transferase TAT. Protein A bound on Sepharose was allowed to react with antiserum preincubated with the enzyme. Inhibition curves in the presence of protein A were parallel to those obtained in the absence of protein A. In the case of cell-free synthesized TAT, the complex bound to the solid phase contains the (35S) labelled enzyme; the sensitivity of the test was greatly increased when the bulk of protein was discarded by pretreatment of the reaction mixture at 70 degree and chromatography on DEAE cellulose. The immunoadsorbed polypeptides were analyzed by dodecylsulfate/polyacrylamide gel electrophoresis. The pattern of polypeptides neosynthesized using RNA from different origins (rat liver, hepatoma cells) and after various treatments (glucocorticoid hormones, sodium butyrate) exhibited some different in the TAT region which can be related to the level of the specific mRNA for TAT. This method is very useful for further studies on TAT gene expression and might also shed light on the mechanism of hormonal action and drug processes.