STRUCTURE AND MAPPING OF THE G-PROTEIN GAMMA-3 SUBUNIT GENE AND A DIVERGENTLY TRANSCRIBED NOVEL GENE, GNG3LG

The mammalian nervous system is rich in signaling mediated by heterotr imeric (alpha beta gamma) G proteins. As an initial step to define the roles that particular gamma subunit types play in signaling, we have begun to clone and characterize those genes that encode gamma subunits enriched within neural tissue. In the present study, we have isolated and characterized the mouse gamma 3 subunit gene (Gng3). The gamma 3 subunit is expressed abundantly in the brain and at low levels in test es. Gng3 is composed of three exons spanning similar to 1.4 kb. A comp arison of Gng3 with the gene structure for five other gamma subtypes i ndicates that although these proteins are diverse at the amino acid le vel, their exon-intron boundaries are conserved. Sequence analysis of the 5' flanking region of Gng3 revealed the presence of a novel gene, the gamma 3 linked gene (Gng3lg). Gng3 and Gng3lg are organized in a h ead-to-head fashion with major transcription initiation sites separate d by approximately 133 bp. Sequence analysis of a Gng3lg cDNA clone re vealed an open reading frame encoding a 410-amino-acid protein of unkn own function. Gng3lg transcripts are expressed in a variety of tissues including both brain and testes. Using an interspecific backcross pan el, we localized both Gng3 and Gng3lg to the same locus on chromosome 19. The orientation, close proximity, and expression pattern of these two genes raise the distinct possibility that shared regulatory elemen ts are used to control their expression. (C) 1998 Academie Press.