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. Author manuscript; available in PMC: 2019 Feb 15.
Published in final edited form as: Gene. 2017 Dec 6;643:133–143. doi: 10.1016/j.gene.2017.12.004

Figure 2. Sequence comparison of human Pur proteins, Pura, Purb and two forms of Purg.

Figure 2

All four of the human protein Pur family members are aligned using the Clustal Omega algorithm. Pura, Purb and Purg-A are each derived from a distinct gene locus. Their entire sequences are aligned at top. Stars indicate amino acid identities; one dot indicates a substitution; two dots indicate a conservative substitution. Purg-B is transcribed from the Purg-A gene locus. Transcription of Purg-B, however, passes through the Purg-A stop point producing a 38 kb intron that is spliced out to make Purg-B mRNA. It is only the C-termini that differ between Purg-A and Purg-B. Sequences of these are presented at the bottom. Vertical lines indicate identities, and 2 dots indicate conservative substitutions. The Psycho motif is lightly underlined in both top and bottom alignments. In Pura it binds the Rb protein, among others (Ma et al., 1994; Johnson et al., 1995), and it is conserved in evolution. It is eliminated in Purg-B. Class 1 (Cl1) and Class2 (Cl2) segments of Pura repeats (R) 1, 2 and 3 are as indicated and heavily underlined.