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TMEM65 is a mitochondrial inner-membrane protein

Naotaka Nishimura1, Tomomi Gotoh2, Yuichi Oike1

  • 1Department of Molecular Genetics, Graduate School of Medical Sciences, Kumamoto University , Kumamoto , Japan.

Peerj
|April 26, 2014
PubMed

Insights

The protein TMEM65 localizes to the inner mitochondrial membrane. This protein is imported into mitochondria and processed by the matrix processing protease (MPP).

Area of Science:

  • Mitochondrial biology
  • Molecular cell biology

Background:

  • The regulation of TMEM65 expression by steroid receptor RNA activator (SRA) has been reported.
  • The intracellular localization and function of TMEM65 remain largely unknown.

Purpose of the Study:

  • To determine the intracellular localization and membrane topology of TMEM65.
  • To elucidate the mechanism of TMEM65 import and processing within mitochondria.

Main Methods:

  • Immunoblot and immunostaining analyses were employed to detect TMEM65.
  • Alkali and digitonin extraction methods were used on isolated mitochondria to assess membrane association.
  • Deletion mutants of TMEM65 were analyzed to identify mitochondrial targeting signals.

Main Results:

  • TMEM65 was found to localize to mitochondria.
  • Further analysis revealed TMEM65 as an integral inner mitochondrial membrane protein.
  • The N-terminal region (1-20) contains a mitochondrial targeting signal (MTS) that is processed between amino acids 35 and 64 by matrix processing protease (MPP).

Conclusions:

  • TMEM65 is imported into mitochondria.
  • TMEM65 integrates into the mitochondrial inner membrane.
  • The protein undergoes proteolytic processing by MPP to reach its mature form.
Keywords:
Inner-membraneMitochondriaMitochondrial targeting signal (MTS)ProcessingTMEM65

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