The mouse male germ cell-specific gene Tpx-1: molecular structure, mode of expression in spermatogenesis, and sequence similarity to two non-mammalian genes.
Tpx-1 is a testis-specific gene that maps on mouse Chromosome (Chr) 17. The deduced TPX-1 protein shows 55% amino acid sequence similarity to acidic epididymal glycoprotein (AEG), assumed to be involved in sperm maturation. In the present study, we determined the genomic structure of the mouse Tpx-1 gene and the cellular localization of its transcripts. The gene was found to contain ten exons, with an unusually large intron (approximately 17.0 kilobase pairs) between exons 8 and 9. In situ hybridization of testicular sections showed that Tpx-1 is transcribed abundantly by haploid male germ cells. A computer search of protein databases revealed that deduced TPX-1/AEG proteins have significant sequence similarity (approximately 30%) to two non-mammalian proteins: "pathogenesis-related" proteins 1 of tobaccos, and venom sac proteins of white-face hornets, known as Dol m V. Amino acid residues encoded by exon 10 of the Tpx-1 gene and most of those encoded by exon 9 were absent in the non-mammalian proteins. This result suggests that the ancestor of Tpx-1 acquired exons 9 and 10 after its divergence from the ancestors of the plant and insect proteins.
Mizuki
N
N
Department of Microbiology and Immunology, University of Miami School of Medicine, Florida 33101.
Sarapata
D E
DE
Garcia-Sanz
J A
JA
Kasahara
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005796:Genes / Q000235:genetics*; D005854:Germ Cells / Q000737:chemistry*; D006023:Glycoproteins / Q000235:genetics*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D011401:Promoter Regions, Genetic / Q000235:genetics; D012671:Seminiferous Tubules / Q000737:chemistry; D012689:Sequence Homology, Nucleic Acid; D013091:Spermatogenesis / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*
D006023:Glycoproteins