The only possible mitochondrial P450 from C.elegans has been reexamined to better identify the intron exon boundaries based on similarity to CYP12A sequences of insects. One previously missed exon is added based on an EST sequence and another exon is extended to fill a critical gap. Only about 40% of the sequence is covered by ESTs, so five of the intron boundaries are theoretical. CELZK177 cosmid ZK177 U21321 CYP44 Probable mitochondrial P450 489 aa C70591 is an EST from the middle region that adds 49 amino acids not previously identified as coding region in ZK177. Another exon extended 13 amino acids helps fill in the missing I-helix region with DGLSTT matching with AGXDTT of the I-helix. * indicates predicted intron locations ** indicates verified introns based on ESTs. MRRSIRNLAENVEKCPYSPTSSPNTPPRTFSEIPGPREIPVIGNIGYFKYAVKS* DAKTIENYNQHLEEMYKKYGKIVKENLGFGRKYVVHIFDP*ADVQTVLAADGKTPFIVPL QETTQKYREMKGMNPGLGNL*NGPEWYRLRSSVQHAMMRPQSVQT*YLPFSQIVSN DLVCHVADQQKRFGLVDMQKVAGRWSLESAGQILFEKSLGSLGNRSEWADGLIEL NKKIFQLSAK**MRLGLPIFRLFSTPSWRKMVDLEDQFYSEVDRLMDDALDKLKVNDSDS** KDMRFASYLINRKELNRRDVKVILLSMFSDGLST*TAPMLIYNLYNLATHPEALKEIQKE IKEDPASSKLTFLRACIKETFRMFPIGTEVSRVTQKNLILSGYEVPAGTAVDINTNVL MR**HEVLFSDSPREFKPQRWLEKSKEVHPFAYLPFGFGPRMCAGRRFAEQDLLTSL AKLCGNYDIRHRGDPITQIYETLLLPRGDCTFEFKKL