The role of alternative mRNA splicing in generating heterogeneity within the Anopheles gambiae class I glutathione S- transferase family

The class I glutathioneS -transferases (GSTs) ofAnopheles gambiae are encoded by a complex gene family. We describe the genomic organization of three members of this family, which are sequentially arranged on the chromosome in divergent orientations. One of these genes,aggst1-2 , is intronless and has been described. In contrast, the twoA. gambiae GST genes (aggst1α andaggst1β ) reported within are interrupted by introns. The geneaggst1α contains five coding exons that are alternatively spliced to produce four mature GST transcripts, each of which contains a common 5′ exon encoding the N termini of the GST protein spliced to one of four distinct 3′ exons encoding the carboxyl termini. All four of the alternative transcripts ofaggst1α are expressed inA. gambiae larvae, pupae, and adults. We report on the involvement of alternative RNA splicing in generating multiple functional GST transcripts. A cDNA from theaggst1β gene was detected in adult mosquitoes, demonstrating that this GST gene is actively transcribed. The percentage similarity of the six cDNAs transcribed from the three GST genes range from 49.5% to 83.1% at the nucleotide level.