Effects of insulin and anchorage on hepatocytic protein metabolism and amino acid transport
| Autor: | P.B. Gordon, Bjørn Grinde, P.E. Schwarze, P.O. Seglen, A. Poli |
|---|---|
| Rok vydání: | 1981 |
| Předmět: |
Male
medicine.medical_treatment Protein metabolism Protein degradation Cycloheximide Biology chemistry.chemical_compound Valine Lysosome Protein biosynthesis medicine Animals Insulin Amino Acids Cells Cultured chemistry.chemical_classification Dose-Response Relationship Drug Aminooxyacetic Acid Proteins Biological Transport Cell Biology Glucagon Rats Amino acid medicine.anatomical_structure Liver chemistry Biochemistry Lysosomes |
| Zdroj: | Journal of Cell Science. 48:1-18 |
| ISSN: | 1477-9137 0021-9533 |
| DOI: | 10.1242/jcs.48.1.1 |
| Popis: | Insulin partially inhibits endogenous protein degradation in isolated hepatocytes. The inhibition seems to specifically affect the lysosomal pathway of degradation, since it is not additive to the effects of lysosome inhibitors such as propylamine and leupeptin. The insulin effect is potentiated by intermediate concentrations of amino acids, but is largely abolished at high amino acid concentrations which suppress degradation maximally, suggesting that the hormone may exert its effect indirectly by acting upon the more basal amino acid control mechanism. Glucagon, which stimulates protein degradation, similarly displays its effect only in the presence of intermediate amino acid concentrations. The insulin inhibition is not affected by the aminotransferase inhibitor, aminooxyacetate, indicating that it is not due to interference with amino acid metabolism. Protein synthesis furthermore does not seem to be required, since a significant insulin effect can be seen in the presence of the protein synthesis inhibitor, cycloheximide. The issue is, however, complicated by the fact that cycloheximide itself inhibits protein degradation to approximately the same extent as does insulin. Insulin stimulates uptake of the amino acid α-aminoisobutyrate (AIB), but not the uptake of valine, indicating a specific stimulation of ‘A’-type transport. Cycloheximide similarly stimulates AIB uptake, without completely obfuscating the transport effect of insulin. Neither protein synthesis, protein degradation, amino acid transport, nor the effects of insulin were affected by cell-to-substratum anchorage (attachment and spreading) in any detectable way. |
| Databáze: | OpenAIRE |
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