| 3B2R: reference: Conformational variations of both phosphodiesterase-5 and inhibitors provide the structural basis for the physiological effects of vardenafil and sildenafil., Wang H, Ye M, Robinson H, Francis SH, Ke H, Mol Pharmacol. 2008 Jan;73(1):104-10. Epub 2007 Oct 24. PMID: 17959709 |
This OCA 
Structure page
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(documentation).