Two forms of expression and genomic structure of the human heterogeneous nuclear ribonucleoprotein D-like JKTBP gene (HNRPDL).

The human DNA- and RNA-binding protein JKTBP is a member of a 2xRNA-binding domain (RBD)-glycine family of heterogeneous nuclear ribonucleoproteins that are involved in mRNA biogenesis. Northern and Western blottings revealed that mRNAs of approx. 1.4 and 2.8kb and proteins of approx. 38 and 53kDa were present in HL-60 cells and various tissues. Cloning and characterization of a previously unknown cDNA for the 2.8kb mRNA indicated that the cDNA encodes a 420 amino acid JKTBP polypeptide. Isolation and characterization of the genomic DNA showed that the gene (HNRPDL) had nine exons and had two separate transcription start sites for the two transcripts. The features of the 5' flanking sequences of these sites showed that the gene is a housekeeping gene. Fluorescence in situ hybridization mapped the gene to 4q13-q21. From its gene organization, the JKTBP seems to be most closely related to hnRNP D/AUF1.