p62/SQSTM1: a missing link between protein aggregates and the autophagy machinery

Autophagy. 2006 Apr-Jun;2(2):138-9. doi: 10.4161/auto.2.2.2405. Epub 2006 Apr 14.

Abstract

In eukaryotic cells short-lived proteins are degraded in a specific process by the ubiquitin-proteasome system (UPS), whereas long-lived proteins and damaged organelles are degraded by macroautophagy (hereafter referred to as autophagy). A growing body of evidence now suggests that autophagy is important for clearance of protein aggregates that form in cells as a consequence of ageing, oxidative stress, alterations that elevate the amounts of certain aggregation-prone proteins or expression of aggregating mutant variants of specific proteins. Autophagy is generally considered to be a non-specific, bulk degradation process. However, a recent study suggests that p62/SQSTM1 may link the recognition of polyubiquitinated protein aggregates to the autophagy machinery.(1) This protein is able to polymerize via its N-terminal PB1 domain and to recognize polyubiquitin via its C-terminal UBA domain. It can also recruit the autophagosomal protein LC3 and co-localizes with many types of polyubiquitinated protein aggregates.(1) Here we discuss possible implications of these findings and raise some questions for further investigation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptor Proteins, Signal Transducing
  • Autophagy / physiology*
  • Humans
  • Microtubule-Associated Proteins / metabolism
  • Protein Binding
  • Protein Structure, Tertiary
  • Proteins / metabolism*
  • Sequestosome-1 Protein
  • Ubiquitin / metabolism*

Substances

  • Adaptor Proteins, Signal Transducing
  • MAP1LC3A protein, human
  • Microtubule-Associated Proteins
  • Proteins
  • SQSTM1 protein, human
  • Sequestosome-1 Protein
  • Ubiquitin