Av. Tsytsykova et al., The mouse genome contains two expressed intronless retroposed pseudogenes for the sentrin/sumo-1/PIC1 conjugating enzyme Ubc9, MOL IMMUNOL, 35(16), 1998, pp. 1057-1067
The ubiquitin conjugating (ubc) E2 enzyme ubc-9 conjugates the ubiquitin-li
ke peptide sentrin/SUMO-1/PIC1 to target proteins which include the Fas ant
igen. We show that the mouse genome contains four copies of the ubc-9 gent.
These include a structural ubc-9 gene consisting of seven exons which enco
de a protein identical to human ubc-9, and three intronless processed pseud
ogenes. The open reading frames (ORF) of two of the pseudogenes, ubc9-psi 1
and ubc9-psi 2, correspond to the cDNA of ubc-9 and encode for proteins wh
ich differ from ubc9 by three and one amino acid substitutions respectively
. The third pseudogene, ubc9-psi 3, contains many mutations and stop codons
. ubc9-psi 1 and ubc9-psi 2 are flanked by 5'- and 3'-untranslated (UT) reg
ions homologous to those of the structural ubc-9 gene. Both gents contain a
polyA tail and direct repeats at both ends suggesting that they arose by m
RNA retroposition. Both ubc9-psi 1 and ubc9-psi 2 are transcribed into mRNA
in murine cells. In contrast to ubc9, the protein products of ubc9-psi 1 a
nd ubc9-psi 2 fail to bind Fas and to complement an yeast conditional ubc9
mutant. These results suggest that ubc9-psi 1 and ubc9-psi 2 encode for pro
teins that may interact with targets that differ from those recognized by u
bc-9. (C) 1999 Elsevier Science Ltd. All rights reserved.