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Walter Neupert

Max Planck Institute of Biochemistry, Munich, Germany

Walter Neupert obtained both his Ph.D. in Biochemistry and his M.D. from the University of Munich. He continued his work there as an assistant professor and lecturer before becoming an associate professor and later professor and chair at the Institute of Biochemistry at the University of G√∂ttingen. Neupert returned to Munich as professor and chair of the Adolf-Butenandt-Institute of Physiological Chemistry, Molecular Biology, Biochemistry and Cell Biology. He has been a Max Planck fellow at the Max-Planck-Institute of Biochemistry in Martinsried, Munich since 2010. 


Molecular mechanisms of mitochondrial homeostasis

Cells continually produce aberrant toxic proteins which are removed by the ribosome associated protein quality control system (RQC) and the ubiquitin proteasome system (UPS). Clearance of nuclear encoded aberrant mitochondrial proteins is particularly critical. Like aberrant cytosolic proteins, they are subject to the addition of alanyl and threonyl residues (CAT-tails) on stalled 60S ribosomal subunits, catalyzed by the Rqc2 component of the RQC. Because their import can occur co-translationally they can escape the UPS. The CAT-tailed proteins then accumulate in the mitochondrial matrix, where they sequester the chaperones and thereby cause massive protein aggregation. This again leads to breakdown of oxidative phosphorylation, mitochondrial protein synthesis and other essential pathways, and to cell death. We describe here how the detrimental role of Rqc2 is counteracted at the 60S ribosomal subunit by the cooperation of three proteins, Vms1, Ltn1 and Arb1.