Table 1 Biological significance of selected validated orphans. The extent and significance of published research associated with a selection of validated orphans is detailed
EC No. | Activity | Year first published | No. PubMed Publications Involving Orphan | Significance |
|---|---|---|---|---|
1.1.1.43 | Phosphogluconate 2-dehydrogenase | 1961 | 2417 | Positive reports of evaluation as a drug target against Trypanosome; trypanocidal activity has been reported; involved in 2-dehydro-D-gluconate degradation pathway |
2.3.1.23 | 1-acylglycerophosphocholine O-acyltransferase | 1967 | 256 | Activity is present in lower eukaryotes, plants, and multiple mammalian tissues |
5.1.3.17 | Heparosan-N- sulfate-glucuronate 5-epimerase | 1979 | 16 | Involved in the biosynthesis of heparan sulfate, which binds proteins to modulate signaling events in embryogenesis. Mouse gene knock-out results in late lethal phenotype. Correction added in proof: Thanks to a comment by Dr. K. Robison and research by Dr. A. Shearer, we have found that 5.1.3.17 is an artifactual orphan rather than a validated orphan. Genes for this enzyme have been identified in cow and mouse (J Biol Chem 272:28158 1997; J Biol Chem 276:20069 2001). |
2.3.1.105 | Alkylglycerophosphate 2-O-acetyltransferase | 1986 | 9 | Involved in platelet activating factor biosynthesis; possible involvement in ischemia |
3.1.3.59 | Alkylacetylglycerophosphatase | 1986 | 9 | Involved in platelet activation factor biosynthesis |
2.7.1.106 | Glucose-1,6-bisphosphate synthase | 1975 | 9 | Present in several mammalian tissues. Involved in glucose metabolism |
1.2.1.23 | 2-oxoaldehyde dehydrogenase (NAD+) | 1967 | 9 | Involved in the development of diabetic complications |
1.14.11.6 | Thymine dioxygenase | 1972 | 9 | Present in both lower and higher eukaryotes |
1.1.1.16 | Galactitol 2-dehydrogenase | 1956 | 5 | Insulin dysregulation |
2.3.1.14 | Glutamine N-phenylacetyltransferase | 1957 | 4 | Investigated as a predictor of carotid endarterectomy in middle-aged individuals |
1.2.1.25 | 2-oxoisovalerate dehydrogenase (acylating) | 1969 | 4 | Present in prokaryotes and eukaryotes. In the latter, participates in primary metabolism pathway for valine degradation |