STRUCTURE, EXPRESSION AND CHROMOSOMAL LOCALIZATION OF HUMAN P80-COILIN GENE

Coiled bodies (CBs) are non-capsular nuclear bodies with a diameter of 0.3-1 mu m and appear to be composed of coiled fibrils. Human autoant ibodies to CBs recognize an 80-kD nuclear protein highly enriched in C Bs, and this protein has been named p80-coilin. CBs are known to assem ble and disassemble during the cell cycle, with the highest number of CBs occurring at mid to late G(1) where p80-coilin is assembled into s everal small nuclear body-like structures. In S and G(2) phases, CBs b ecome larger and their number decreases and often they are undetectabl e during mitosis. Using a human autoantibody as a probe for expression cloning, we initially isolated a partial cDNA encoding p80-coilin. In this report, the 5' end of the complete cDNA for p80-coilin was obtai ned using the 5'-RACE (rapid amplification of cDNA ends) methodology. The size of the reconstructed full-length cDNA corresponds to the 2.7- kb mRNA detected in Northern blot analysis. The complete p80-coilin pr otein consists of 576 amino acids with a predicted molecular mass of 6 2,608. A putative p80-coilin pseudogene was also detected during the r escreening of p80-coilin cDNA. To confirm the validity of the cDNA seq uence, three overlapping genomic DNA clones representing the human p80 -coilin gene were selected for further analysis. The complete gene for p80-coilin contains 7 exons spanning similar to 25kb. Sequence analys is of exons 1 and 2 in genomic DNA clones confirmed the accuracy of th e 5' cDNA sequence derived from the 5'-RACE procedure. Furthermore, th e human p80-coilin gene was localized to chromosome 17q22-23 by fluore scence in situ hybridization.