ZZ domains keep cytosol to vacuole delivery whiZZing along

NBR1: The archetypal selective autophagy receptor

NBR1 was discovered as an autophagy receptor not long after the first described vertebrate autophagy receptor p62/SQSTM1. Since then, p62 has currently been mentioned in >10,000 papers on PubMed, while NBR1 is mentioned in <350 papers. Nonetheless, evolutionary analysis reveals that NBR1, and likely also selective autophagy, was present already in the last eukaryotic common ancestor (LECA), while p62 appears first in the early Metazoan lineage. Furthermore, yeast-selective autophagy receptors Atg19 and Atg34 represent NBR1 homologs. NBR1 is the main autophagy receptor in plants that do not contain p62, while most animal taxa contain both NBR1 and p62. Mechanistic studies are starting to shed light on the collaboration between mammalian NBR1 and p62 in the autophagic degradation of protein aggregates (aggrephagy). Several domains of NBR1 are involved in cargo recognition, and the list of known substrates for NBR1-mediated selective autophagy is increasing. Lastly, roles of NBR1 in human diseases such as proteinopathies and cancer are emerging.

ZZ domains keep cytosol to vacuole delivery whiZZing along

Selective autophagy relies on adaptor proteins to bind and transport cargos (or substrates) to the lysosome or vacuole, yet the mechanisms for cargo recognition are not well understood. In this issue, Wang et al (2021) showed that in the fission yeast, Nbr1, a homolog of a mammalian selective autophagy adaptor, recognizes vacuolar hydrolases Ams1 and Ape4 through both versatile and cargo-specific interactions with the Nbr1 ZZ1 domain.