抄録
Ferritin is an iron storage protein with a wide distribution in animal cells. It consists of outer protein shell (apoferritin) and inner iron cores. Recent advance of radioimmunoassay enabled us to detect a trace amount of ferritin in serum. To evaluate the clinical and pathophysiological significance of serum ferritin, it would be worthy to have a basic knowledge about the charateristics of ferritin molecules. In this paper, we performed analysis of human, rat, and horse ferritins electrophoretically and immunologically and the results were obtained as follows:
1) All tissue ferritins showed multiple forms designated as isoferritin, when analyzed by isoelectric focusing. In human and rat, the heart ferritins were more acidic than the liver or spleen ferritins and vise versa in horse.
2) By subunit analysis using SDS/polyacrylamide gel electrophoresis, all ferritin molecules were fashioned from a set of subunits, H and L and the hetergeneous profiles on IEF were reflecting the different proportion of these subunits. Therefore it was suggested that ferritin is a hybrid molecule composed of two dissimilar subunits.
3) Isoferritiins from different tissues varies qualitatively and quantitavely in their immunological reactivities and these differences pararelled the proportion of H and L subunits.
4) The long term iron administration to rats showed a shift of liver isoferritin profile to more basic pI range, which supports the similar obseration of phenotypic shift of ferritins in haemochromatosis tissues.
5) Two types of subunits of ferritin molecules were demonstrated in a cell free synthesizing system of wheat germ lysate programmed by rat liver mRNA, indicating that these two subunits are indeed primary gene product.
