Expression of multiple proteins structurally related to gamma-glutamyl transpeptidase in non-neoplastic adult rat hepatocytes in vivo and in culture
| Autor: | Alphonse E. Sirica, Georg A. Mathis, Rebecca P. Hughey, Peter A. Wyss, Erin G. Schuetz |
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| Rok vydání: | 1991 |
| Předmět: |
Male
Physiology Clinical Biochemistry Blotting Western Biology digestive system In vivo Gene expression medicine Animals Northern blot RNA Messenger Protein precursor Cells Cultured chemistry.chemical_classification Messenger RNA Kidney Cell Biology gamma-Glutamyltransferase Blotting Northern Molecular biology digestive system diseases Rats Inbred F344 Rats Kinetics Enzyme medicine.anatomical_structure Biochemistry chemistry Liver Organ Specificity Enzyme Induction Isotope Labeling Female Glycoprotein |
| Zdroj: | Journal of cellular physiology. 146(2) |
| ISSN: | 0021-9541 |
| Popis: | Freshly isolated hepatocytes from normal adult rat liver do not express measurable gamma-glutamyl transpeptidase (GGT) mRNA in contrast to the significant GGT mRNA levels expressed by normal adult rat kidney and hyperplastic bile ductular tissue from bile duct-ligated rats. However, the induction of GGT activity in rat hepatocytes by two-thirds hepatectomy was accompanied by the appearance of a high level of GGT mRNA. We are now able to demonstrate that normal adult rat hepatocytes express 5 protein bands which cross-react with 2 different anti-rat kidney GGT antisera. The apparent molecular weights were 26.9, 58.0, 63.9, 73.5, and 83.4 kDa, respectively. Expression of the 26.9- and 58.0-kDa proteins strikingly parallels the pattern of induction of GGT enzymatic activity. This suggests that these 2 proteins correspond to the active dimeric enzyme previously described in kidney and neoplastic hepatocellular tissue. In normal hepatocytes, the 73.5-kDa protein represents 50% of the total GGT-immunoreactive protein, in contrast to kidney, where this band contains less than 4% of the GGT protein. The kinetics of expression of the 73.5-kDa protein upon induction of GGT activity in hepatocytes, as well as in culture turnover studies, suggests that this protein is a precursor form of the active enzyme, such as the described 78/79-kDa single-chain glycoprotein propeptide of GGT. It appears that in normal hepatocytes, this precursor is not processed to the same extent as in kidney or in hyperplastic bile ductular tissue. |
| Databáze: | OpenAIRE |
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