GENOMIC ORGANIZATION OF THE MOUSE FERTILIN BETA-GENE THAT ENCODES AN ADAM FAMILY PROTEIN ACTIVE IN SPERM-EGG FUSION

The fertilin alpha and beta genes (Ftna and Ftnb. respectively) encode a sperm surface heterodimer that functions in sperm-egg fusion. They are the first identified members of a large gene family coding for mul tidomain membrane proteins (ADAMs) that include A Disintegrin And Meta lloprotease domain. In this study we report the isolation and structur al organization of the mouse fertilin beta gene. The gene is present a s a single copy and covers a region of approximately 55 kilobases in t he genome. The fertilin beta gene is composed of at least 20 exons int errupted by 19 introns. The sizes of the exons are relatively small an d vary from 56 to 193 bases: the sizes of introns vary from 350 bases to 9.4 kilobases. The exon-intron boundaries conform to the GT/AG rule with one exception. GC replaces GT at the 5' splice site in intron 13 . Comparison of genomic organization between mouse fertilin beta and t he previously sequenced ADAM family gene, human MDC [Katagiri et al. ( 1995): Cytogenet Cell Genet 68:39-44] showed 12 conserved exon-intron boundaries. In addition, we analyzed the fertilin alpha gene, demonstr ating that more than one gene is present in the mouse genome. (C) 1997 Wiley-Liss, Inc.