Sequence alignment of Vpr proteins from two different origins.

Single letter code for amino acids (aa) is used. The three α-helixes are Helix I, aa 17–33, Helix II, aa 38–50 and Helix III, aa 56–77. Variable sequence of the PP2A1 binding domain (77–92) is in red. Non variable sequence of mitochondrial death domain is in italic (71–82). *Asterisks indicate distinct residues in 89.6-Vpr (accession number: AAA81039) and VprpNL4.3 (accession number: AF324493) that are located in PP2A1 binding domain. Mutational studies in yeast, suggested that the T89A substitution in NL4.3-Vpr has no apoptotic effect [46]. The K95R substitution in 89.6-Vpr is outside of PP2A1-death domain.