| Autor: |
Helmut W. Klein, Richard C. Cantrill, Reiner Peters, Helmuth Heithier, Larry W. Ward, Ernst J.M. Helmreich |
| Rok vydání: |
1988 |
| Předmět: |
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| Zdroj: |
Berichte der Bunsengesellschaft für physikalische Chemie. 92:973-978 |
| ISSN: |
0005-9021 |
| DOI: |
10.1002/bbpc.198800243 |
| Popis: |
New fluorescent glucagon derivatives were synthesized by converting tryptophan25 to 2-thiol-tryptophan with the consequent use of thiol specific fluorescent reagents. All derivatives retained the ability to bind tightly to rat liver membranes and rat hepatocytes in primary culture and to activate adenylate cyclase as potently as native glucagon. Thus these derivatives are full agonists. From experiments with monolayer cultured hepatocytes and 125I-glucagon at elevated temperatures it was assumed that the ligand was internalised at this temperature since some of the specifically bound ligand could no longer be washed off with acid. This was confirmed in experiments where monolayer cultures of hepatocytes were incubated with the fluorescein-labelled derivates of glucagon, thus allowing the study of the distribution of glucagon specifically bound on the cell surface using video intensification microscopic techniques. In keeping with autoradiographic studies using radiolabelled glucagon, or electron microscope studies using ferritin labelled glucagon, we could now show using fluorescently labelled glucagon derivatives and video intensification microscopy that at lower temperatures the bound ligand was distributed all over the cell surface. Whereas, at the higher temperature, ligand derived fluorescence could only be detected in mobile intracellular vesicles following internalisation and removal from the cell surface. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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