Adenosine 5'-triphosphate modulation of nitrobenzylthioinosine binding sites in plasma membranes of bovine chromaffin cells
| Autor: | Teresa Casillas, Esmerilda G. Delicado, M. Teresa Miras-Portugal |
|---|---|
| Rok vydání: | 1993 |
| Předmět: |
Adenosine monophosphate
Nucleoside transporter chemistry.chemical_compound Adenosine Triphosphate Thioinosine medicine Centrifugation Density Gradient Enterochromaffin Cells Animals Binding Sites biology Adenylyl Imidodiphosphate General Neuroscience Cell Membrane Adenosine Kinetics medicine.anatomical_structure chemistry Biochemistry Chromaffin cell biology.protein Cattle Ap4A Adenosine triphosphate Nucleoside medicine.drug |
| Zdroj: | Neuroscience letters. 164(1-2) |
| ISSN: | 0304-3940 |
| Popis: | Nitrobenzylthioinosine (NBTI) is a high affinity probe for facilitated diffusion nucleoside transporters. Kinetic analysis of the binding of [3H]NBTI to plasma membranes of chromaffin cells was conducted in the presence or absence of adenosine 5'-triphosphate (ATP). Similar curvilinear plots with a Hill number of 1.32 were obtained in both conditions. ATP significantly increased the number of NBTI binding sites in these preparations showing Bmax values of 1.62 +/- 0.20 pmol/mg protein for controls and 3.22 +/- 0.31 pmol/mg protein in the presence of ATP. However, the affinity constant (KD) was not significantly modified. The non-metabolizable ATP analogue, 5'-adenylyl imidodiphosphate (AMP-PNP) and diadenosine tetraphosphate (Ap4A) can mimic the stimulatory ATP effect, but adenosine monophosphate (AMP) has no effect on the NBTI binding to plasma membranes. These results indicate a modulatory role for ATP, non-hydrolysis dependent, on nucleoside transport in chromaffin cells. Therefore, a nucleotide binding site on the nucleoside transporter similar to that described for glucose transporter could be suggested. |
| Databáze: | OpenAIRE |
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