Protein quality control

Mitochondrial-derived vesicles (MDVs) transfer mitochondrial content to lysosomes and peroxisomes. A study now reveals that MDVs deliver β-barrel proteins and fully assembled mitochondrial complexes for lysosomal degradation, establishing an important role for MDVs in mitochondrial protein quality control.

Neuronal mitochondria perturbation elicits a mitochondrial unfolded protein response (UPR^mt) in peripheral tissues cell non-autonomously, dependent on the Wnt signalling pathway. A study now reveals that a Wnt-mediated increase in maternally inherited mitochondria DNA is responsible for transgenerational UPR^mt induced by neuronal mitochondria perturbation.

The ‘N-end rule’ correlates the identity of the N-terminal residue of a protein to its in vivo half-life. A study has now shown that an N-terminal glycine can serve as a potent degradation signal, which reveals a novel branch of N terminus–dependent protein degradation.

In the ribosome-associated quality control (RQC) pathway, stalled ribosomes are ubiquitinated and dissociated into subunits. The nascent protein chain associated with the 60S ribosomal subunit is ubiquitinated by the E3 ligase Listerin (Ltn1) and is released from tRNA by ANKZF1 (Vms1) for proteasomal degradation. Shao and colleagues now report that ANKZF1 (Vms1)-cleaved tRNAs are recycled via a two-step process that requires the removal of a terminal 2′,3′-cyclic phosphate and the addition of CCA by TRNT1.