STRUCTURE AND ORGANIZATION OF GABRB3 AND GABRA5

The genes encoding the gamma-aminobutyric acid (GABA) type-A receptor subunits beta 3 (GABRB3), alpha 5 (GABRA5), and gamma 3 (GABRG3) map t o chromosome 15q11-q13. The three genes are contained within roughly 8 00 kb of the distal part of the imprinted Prader-Willi and Angelman sy ndrome region. A 570-kb contig encompassing GABRB3 and GABRA5 has been constructed in P1, lambda phage, and PAC clones. GABRB3 spans 250 kb of DNA and is organized into 9 exons that range from 68 to 504 bp, whi le GABRA5 is encoded by 11 exons (65 to 924 bp in length) within 86 kb . The exon/intron borders for both genes have been characterized, and primers have been designed to amplify each of the individual exons. Tw o reference STR markers have been positioned in the contig. The refere nce STR for GABRB3 is in fact located at least 60 kb beyond the 3' ter minus of GABRB3, while D15S97 is contained within intron 4 of GABRB3. The detailed physical map of this GABA(A) receptor subunit gene cluste r should not only be useful in genetic studies of the 15q11-q13 region , but will also be important for investigating the evolution and expre ssion of the GABAA receptor gene superfamily. (C) 1997 Academic Press.