Abstract
A 2A adenosine receptors were examined in bovine striatal membranes following exposure to tetranitromethane (TNM) which modifies tyrosine and cysteine residues. TNM (0.05–0.5 mM) treatment caused an irreversible, concentration-dependent decrease in the binding activity of the selective A 2A agonist [ 3H]CGS 21680. Protection studies showed that TNM inactivation could be prevented by the adenosine receptor agonist 5′- N-ethylcarboxamidoadenosine (NECA) and by the antagonist xanthine amine congener (XAC), suggesting that TNM modified residues at the ligand-binding sites. Scatchard analysis of the binding data showed that 0.15 mM TNM decreased the [ 3H]CGS 21680 B max value from 447±39 to 273±21 fmol/mg of proteins without any significant change in the K d values (13.5±1.4 and 14.7±1.5 for control and treated membranes, respectively). We carried out a series of successive chemical modifications with the reducing agent dithiothreitol (DTT), which indicated that the residues modified by TNM, under our experimental conditions, are tyrosine residues and not cysteine residues.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Biochimica et Biophysica Acta (BBA) - Biomembranes
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
