GENOMIC ORGANIZATION OF A MOUSE GLYCERALDEHYDE-3-PHOSPHATE DEHYDROGENASE GENE (GAPD-S) EXPRESSED IN POSTMEIOTIC SPERMATOGENIC CELLS

The Gapd-s gene encodes an isoform of the glyceraldehyde 3-phosphate d ehydrogenase enzyme expressed only in post-meiotic spermatogenic cells . Two clones containing the Gapd-s gene were isolated from a mouse gen omic library. Sequencing and restriction enzyme analysis demonstrated that this single-copy gene contains 11 exons and spans 9596 base pairs . The locations of Gapd-s exons and introns are conserved when compare d to the corresponding portions of the chicken and human somatic Gapd genes. The promoter region contains no TATA box, although there is a p otential SP1 recognition site within exon 1. Like other TATA-less gene s, primer extension analysis reveals some heterogeneity in the site of transcription initiation with Gapd-s transcripts initiating from thre e discrete sites. Northern analysis demonstrated that a 1.5-kb Gapd-s mRNA is expressed in the testis in at least three mammalian orders, in dicating that the Gapd-s gene appeared early in mammalian evolution. U sing GAPD-deficient bacteria, mouse GAPD-S was shown to be capable of functioning as a glycolytic enzyme. Since GAPD has been proposed to be a key enzyme regulating glycolysis in spermatogenic cells, GAPD-S may represent a potential target for toxicological or contraceptive agent s affecting fertility by interfering with glycolysis. (C) 1995 Wiley-L iss, Inc.