CLONING, SEQUENCING, AND CHROMOSOMAL LOCALIZATION OF 2 TANDEMLY ARRANGED HUMAN PSEUDOGENES FOR THE PROLIFERATING CELL NUCLEAR ANTIGEN (PCNA)

We have characterized a human genomic clone carrying two pseudogenes f or the proliferating cell nuclear antigen (PCNA), which were tandemly arranged on human Chromosome (Chr) 4. One is a processed pseudogene th at showed a 73% nucleotide homology to the human PCNA cDNA and possess ed none of the introns existing in the functional PCNA gene. This pseu dogene presumably arose by reverse transcription of a PCNA mRNA follow ed by integration of the cDNA into the genome. The other is a 5' and 3 ' truncated pseudogene that showed a nucleotide homology to a 3' regio n of the exon 4 and to a 5' region of the exon 5 of the PCNA gene and did not have the intronic sequence between the exons 4 and 5. Both pse udogenes had the same nucleotide deletion as compared with the human f unctional PCNA gene. A phylogenetic analysis of PCNA gene family, incl uding the functional PCNA gene and another PCNA pseudogene located on a different chromosome, revealed that the truncated pseudogene exhibit s the closest evolutionary relationship with the processed pseudogene, suggesting that the truncated pseudogene was generated by duplication of the processed pseudogene after translocation to Chr 4. Furthermore , fluorescence in situ hybridization revealed that these pseudogenes a re located on the long arm of Chr 4, 4q24.