Fig. 1.

Drosophila Sap-r is expressed in glia. A. The Drosophila prosaposin homologue Saposin-related (dSap-r) consists of seven exons and is present on the right arm of the third chromosome (3R) at position 100A7. The dSap-r gene contains two potential transcript start sites (ATG), which result in the production of a transcript consisting of the entire coding sequence (dSap-rRA, 3451 bp) and an in-frame, truncated version (dSap-rRB, 3349 bp) (black lines). The dSap-r^C27 mutant allele was generated by P-element mobilisation from the P{GawB}NP7456 line and is a 2.5 kb deletion. The dSap-r^PBac mutant allele consists of a 5.971 bp piggyBac transposon insertion into the largest dSap-r exon. The deletion in the deficiency line Df(3R)tll-e spans cytogenetic bands 100A2–100C5, which includes the dSap-r gene. B. A Clustal X alignment of the 8 predicted Drosophila melanogaster saposins (dSaps) and the 4 Homo sapiens saposins (hSaps). Asterisks, conserved cysteine residues; underlining, glycosylation sites in each hSap and possible homologous sites in the dSaps. Blue highlights identical residues; yellow highlights similar residues (80% threshold setting). C. Confocal images of third instar larvae brains expressing mCD8eGFP or eIF4AIIIGFP (n > 5) under the control of dSap-r^NP7456 GAL4 and stained with α-repo (glial nuclear marker) or α-elav (pan neuronal marker). Scale bars: 20 μm.