Truncated RanGAP Encoded by the Segregation Distorter Locus of Drosophila

Abstract

Segregation Distorter (SD) inDrosophila melanogaster is a naturally occurring meiotic drive system in which the SD chromosome is transmitted fromSD/SD⁺ males in vast excess over its homolog owing to the induced dysfunction of SD⁺-bearing spermatids. The Sd locus is the key distorting gene responsible for this phenotype. A genomic fragment from theSd region conferred full distorting activity when introduced into the appropriate genetic background by germline transformation. The only functional product encoded by this fragment is a truncated version of the RanGAP nuclear transport protein. These results demonstrate that this mutant RanGAP is the functional Sd product.