ZONATION OF METABOLISM AND GENE-EXPRESSION IN LIVER

The zonation of gene expression resulting in the different cellular equipment of liver cells with enzymes, translocators and subcellular structures is regulated mainly at a pretranslational level. In the dynamic zonation of carbohydrate metabolizing enzymes, gradients in oxygen and in the glucagon/insulin ratio decreasing from the periportal to the perivenous area appear to be major effectors. In the stable zonation of ammonia-metabolizing enzymes local paracrine cell-cell interactions via diffusible mediators could play a major role (Fig. 6). © 1995 Springer Verlag.