MOLECULAR-CLONING AND CHARACTERIZATION OF THE BOVINE AND PORCINE OUTER DENSE FIBERS CDNA AND ORGANIZATION OF THE BOVINE GENE

Outer dense fibers (ODF) or accessory fibers are filamentous structure s of the sperm tail of many eumetozoan organisms endowed with internal fecundation, The bovine and porcine cDNA of an outer dense fiber prot ein was cloned, sequenced and compared to the previously characterized human and rat cDNA sequences, The coding sequences and the 5' and 3' untranslated regions of the ODF cDNAs are highly conserved, A comparis on of the bovine, porcine, human and rat ODF protein sequences reveale d that the protein displays a high degree of similarity, ranging from 87% to 98%, The ODF protein is rich in cysteine and contains the C.X.P . repeat at the C-terminal which is different in number among mammalia n species, All the 27 cysteine residues in the ODF sequence except tho se in the C.X.P. repeat are conserved in the four species, We report h ere also the organization of the bovine ODF gene which is similar to t hat of human and rat. The transcription start site in the bovine ODF g ene is localized 98 bp upstream of the translation start site. Alignme nt of the 5'flanking region of bovine ODF with the rat gene reveals th at the first 130 nucleotides upstream of the transcription start site exhibit an overall sequence similarity of 83%. This conserved region c ontains a TATA-like box (TTTAAA) and binding sites for AFT/CREB and EG R-1 transcription factors.