Genomic organization of the mouse fertilin β gene that encodes an ADAM family protein active in sperm-egg fusion

Abstract

The fertilin α and β 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 multidomain membrane proteins (ADAMs) that include A Disintegrin And Metalloprotease domain. In this study, we report the isolation and structural organization of the mouse fertilin β gene. The gene is present as a single copy and covers a region of approximately 55 kilobases in the genome. The fertilin β gene is composed of at least 20 exons interrupted by 19 introns. The sizes of the exons are relatively small and 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 β and the 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 α gene, demonstrating that more than one gene is present in the mouse genome.