Interaction of Leu-enkephalin with isolated enterocytes from guinea pig: binding to specific receptors and stimulation of cAMP accumulation |
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| Authors: | M P López-Ruiz E Arilla A Gómez-Pan J C Prieto |
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| Affiliation: | 1. The Key Laboratory of Beam Technology and Material Modification of Ministry of Education, College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China;2. School of Nuclear Science and Technology, University of South China, Hengyang 421001, China;3. School of Materials Science and Engineering, Anhui University of Science & Technology, Huainan 232001, China;4. Beijing Radiation Center, Beijing 100875, China;5. Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000, China |
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| Abstract: | The specific binding of Leu-enkephalin and the stimulatory effect of the peptide on cAMP accumulation have been assessed in isolated enterocytes of guinea pig. The binding was reversible as well as time and temperature dependent. Two classes of binding sites could be defined: a class with a relatively high affinity (Kd = 0.7 microM) that represented 1% of total binding capacity, and another class with low affinity (Kd = 55.5 microM). The stimulation of cAMP accumulation was also shown to depend on time and temperature and was potentiated by a phosphodiesterase inhibitor. Half-maximal stimulation of cAMP accumulation was observed at 119 microM and maximal stimulation (27-fold basal level) at 300 microM Leu-enkephalin. Both steps of the interaction were not modified by Na+ but exhibited a high specificity since modification in the structure of Leu-enkephalin resulted in an important loss of binding affinity and stimulatory activity. |
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