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 mapp ed on chromosome 14, as well as on chromosome 19, suggesting that two close ly related copies of the same gene might exist in the human genome. We repo rt here that the gene localized on chromosome 14 corresponds to a highly ho mologous processed pseudogene related to hnRNP I gene (psi hnRNP I). Analys is by RT-PCR and by EST database comparison indicates that psi hnRNP I is n ot 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 int ron-exon boundaries unveiled the possible mechanism by which three isoforms of the protein (namely hnRNP I: PTB2 and PTB3) are generated by means of a lternative splicing of the same hnRNP I gene transcript. (C) 2000 Elsevier Science B.V. All rights reserved.