Organization of the human gene encoding heterogeneous nuclear ribonucleoprotein type I (hnRNP I) and characterization of hnRNP I related pseudogene.

The human gene hnRNP I encoding the heterogeneous nuclear ribonucleoprotein type I, an alternative splicing modulator of tissue-specific transcripts, also known as PTB (polypyrimidine tract-binding protein), was recently mapped on chromosome 14, as well as on chromosome 19, suggesting that two closely related copies of the same gene might exist in the human genome. We report here that the gene localized on chromosome 14 corresponds to a highly homologous processed pseudogene related to hnRNP I gene (yhnRNP I). Analysis by RT-PCR and by EST database comparison indicates that yhnRNP I is not expressed. In this report we have also analyzed the organization of the actual hnRNP I gene localized on chromosome 19. The DNA sequence at the intron-exon boundaries unveiled the possible mechanism by which three isoforms of the protein (namely hnRNP I, PTB2 and PTB3) are generated by means of alternative splicing of the same hnRNP I gene transcript. (C) 2000 Elsevier Science B.V. All rights reserve...