Association of a novel mitochondrial protein m19 with mitochondrial nucleoids

Megumi Sumitani, Katsumi Kasashima, Eriko Ohta, Dongchon Kang, Hitoshi Endo

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)


We have identified a novel mitochondrial protein, termed M19, by proteomic analysis of mitochondrial membrane proteins from HeLa cells. M19 is highly conserved among vertebrates, and possesses no homologous domains with other known proteins. By northern and western blotting, mouse M19 was shown to be expressed in various tissues, and to be especially abundant in the brain. Human M19 (hM19) is present in mitochondria, and protease-protection experiment showed it to be sublocalized in the matrix space. Carboxy-terminally tagged hM19 appeared as spotted signals within mitochondria and co-localized with signals arising from mitochondrial DNA (mtDNA), suggesting the inclusion of M19 in the mtDNAprotein complex (mitochondrial nucleoids). Fractionation of mitochondrial nucleoids from HeLa cells revealed that hM19 has a similar distribution pattern like that of known nucleoid components, such as mtSSB and PHBs, and surely exists in the nucleoid fraction. Furthermore, expression of M19 is closely related to the amount of mtDNA, because it was down-regulated in mtDNA-depleted ρ0 HeLa cells. These results indicate that M19 associates with the nucleoid and likely regulates the organization and metabolism of mtDNA.

Original languageEnglish
Pages (from-to)725-732
Number of pages8
JournalJournal of biochemistry
Issue number5
Publication statusPublished - Nov 2009

All Science Journal Classification (ASJC) codes

  • General Medicine


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