1VPU:
reference: Secondary structure and tertiary fold of the human immunodeficiency virus protein U (Vpu) cytoplasmic domain in solution., Willbold D, Hoffmann S, Rosch P, Eur J Biochem 1997 May 1;245(3):581-8. PMID: 9182993

This OCA Structure page
uses Jmol, developed by the Jmol Development Team (documentation).