ADAM family genes testase 2 alpha and 2 beta are chromosomally linked and simultaneously expressed in male germ cells

Abstract

The ADAM (a disintegrin and a metalloprotease) family includes the best-characterized proteins involved in gamete interaction and membrane fusion in mammals. Previous studies have shown that the murine testase 2 (ADAM 25) gene is expressed specifically in testis. We found two different restriction patterns of subdoned fragments of the gene, indicating the presence of two different testase 2 transcripts. Further experiments and Celera database searches demonstrated that the two transcripts are the products of two testase 2 genes, which are located on mouse chromosome 8 in close distance of 24 kb. They show high sequence similarity to the published testase 2 gene (87.8 and 95.5%, respectively). The genomic structure of both testase 2 genes (alpha and beta) is different from other ADAM family genes like that for cyritestin and fertilin. While these genes are composed of about 20 exons, the testase 2alpha and 2beta genes contain only two exons. The first exon is very short similar to85 bp while the second exon is similar to2.4 kb long. Both testase 2 genes are specifically expressed in testis and they exhibit the same temporal and spatial expression pattern during male germ cell differentiation with the onset of expression in haploid stages. (C) 2003 Wiley-Liss, Inc.