Dolichol-phosphate-mannose (DPM) synthase is an evolutionary conserved protein complex localized to the endoplasmic reticulum and comprises three subunits (reviewed in PMID:18387370). The D. melanogaster catalytic subunit, DPM1, has been identified in a few papers (FBrf0228609, FBrf0214472, FBrf0207984), though has not been characterized in detail. DPM2 and DPM3 have not been identified to date.
I used 3 different approaches to identify all the D. melanogaster OST subunits:
1. Current Gene Ontology (GO) annotations to fly genes using the terms "dolichol-phosphate-mannose synthase complex" (GO:0033185) and "dolichyl-phosphate beta-D-mannosyltransferase activity" (GO:0004582).
2. D. melanogaster orthologs of the 3 human DPM subunits (determined using the HCOP/DIOPT tools) listed in the DPM gene group at the HGNC site (https://www.genenames.org/data/genegroup/#!/group/1893).
3. Searching using the InterPro domains "DPM1-like" (IPR039528), "Dolichol phosphate-mannose biosynthesis regulatory" (IPR009914) and "Dolichol-phosphate mannosyltransferase subunit 3 (IPR013174).
The resulting three D. melanogaster genes are:
FBgn	gene_sym	human_ortholog
FBgn0032799	CG10166	DPM1
FBgn0259933	CG42456	DPM2
FBgn0053977	CG33977	DPM3