title: Novel eye-specific calmodulin methylation characterized by protein mapping in Drosophila melanogaster.
abstract: Post-translational methylation of the epsilon-amino group of lysine residues regulates a number of protein functions. Calmodulin, a key modulator of intracellular calcium signaling, is methylated on lysine 115 in many species. Although the amino acid sequence of calmodulin is highly conserved in eukaryotes, it has been shown that lysine 115 is not methylated in Drosophila calmodulin and no other methylation site has been reported. In this study, we characterized in vivo modification states of Drosophila calmodulin using proteomic methodology involving the protein mapping of microdissected Drosophila tissues on 2-D gels. We found that Drosophila calmodulin was highly expressed in methylated forms in the compound eye, whereas its methylation was hardly detected in other tissues. We identified that lysine 94 located in an EF-hand III is the methylation site in Drosophila calmodulin. The predominance of methylated calmodulin in the compound eye may imply the involvement of calmodulin in photoreceptor-specific functions through methylation.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73190, USA.
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Takemori
authors.forename: Naoka
authors.initials: N
authors.lastname: Komori
authors.forename: James N
authors.initials: JN
authors.lastname: Thompson
authors.forename: Masa-Toshi
authors.initials: MT
authors.lastname: Yamamoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumoto
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002147:Calmodulin / Q000737:chemistry / Q000378:metabolism*; D030562:Databases, Protein; D004331:Drosophila melanogaster / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D005123:Eye / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008297:Male; D013058:Mass Spectrometry; D008745:Methylation; D008958:Models, Molecular; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010449:Peptide Mapping / Q000379:methods*; D040901:Proteomics / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014357:Trypsin / Q000494:pharmacology
chemical_list: D002147:Calmodulin; D012333:RNA, Messenger; D014357:Trypsin; D008239:Lysine