Itisstandardpractice,wheneveraresearcherfindsanewgene,tosearchdatabasesforgenesthathaveasimilarsequence.Itisnotstandardpractice,wheneveraresearcherfindsanewgene,tosearchforgenesthathavesimilarexpression(coexpression).Failuretoperformco-expressionsearcheshasleadtoincorrectconclusionsaboutthelikelyfunctionofnewgenes,andhasleadtowastedlaboratoryattemptstoconfirmfunctionsincorrectlypredicted.WepresentheretheexampleofGliaMaturationFactorgamma(GMF-gamma).Despiteitsname,ithasnotbeenshowntoparticipateingliamaturation.ItisageneofunknownfunctionthatissimilarinsequencetoGMF-beta.ThesequencehomologyandchromosomallocationledtoanunsuccessfulsearchforGMF-gammamutationsinglioma.WeexaminedGMF-gammaexpressionin1432humancDNAlibraries.Highestexpressionoccursinphagocytic,antigen-presentingandotherhematopoieticcells.WefoundGMF-gammamRNAinalmosteverytissueexamined,withexpressioninnervoustissuenohigherthaninanyothertissue.OurevidenceindicatesthatGMF-gammaparticipatesinphagocytosisinantigenpresentingcells.Searchesforgeneswithsimilarsequencesshouldbesupplementedwithsearchesforgeneswithsimilarexpressiontoavoidincorrectpredictions.
