Structure and Expression of the Murine Annexin A9 Gene

ABSTRACT: AnnexinA9isarecentlyidenti”edmember oftheannexingenefamily.TheproductstheevolutionarilyrelatedannexingenesarebiochemicallydescribedbytheirCa 2C -dependentbindingtomembranephospholipids.AnnexinA9isuniquewithinthefamily,inasmuchasitscDNA-derivedpro-teinsequencepredictsalossofhigh-af”nityCa 2C bindingsites.InordertounderstandthemostlikelyunusualandCa 2C -insensitiveroleofannexinA9,weanalyzedthestructureandexpressionofitsgene.WereporthereonthecompletegenomicstructureofmurineannexinA9,showingthepresenceofanuntranslated”rstexonwithuniquefeatures,possiblyresponsibleforthelowAnxA9expressionlevelsgenerallyobserved.Thegeneisexpressedearlyinembryonicdevelopmentandverymarginallyinspe-ci”cadulttissues.Suchanexpressionpatternisatypicalformostannexinsandcouldbeanindicationofaspecializedfunction. Keywords: AnnexinA9,AnxA9,Annexins,AnnexinExpression. 1.INTRODUCTION AnnexinA9(formerlyannexinXXXI,annexin31)isanewlyidenti”edmemberoftheannexingenesuperfamily.Thehumangene(ANXA9)wasat”rstidenti”edthroughsystematicanalysisofexpressedsequencetags(ESTs)indbESTcDNAclonesfromfetalliver/spleenlibraries[1].Lateron,themouseorthologue(AnxA9)wasdescribedasamouseskincDNAclone(GenBankaccessionnos.NM_023628,AJ401160).ThehumanANXA9genewasmappedtochromosome1q21andmouseAnxA9tothesynthenicchromosome3inanalogouslocation.Bysequencecomparisonitwasshownthattheextanthomo-logueclosesttoannexinA9isannexinA2.TheannexinA9proteinexhibits¹40%similaritywithannexinA2,andthetwogenesseemtohaveacommonannexinancestor[2].