Quality control pathways of tail-anchored proteins

Area of Science:

• Cell Biology
• Protein Trafficking
• Membrane Biology

Background:

• Tail-anchored (TA) proteins possess a cytosolic N-terminal domain and a C-terminal transmembrane anchor, directing them to various organelle membranes.
• Mistargeting of TA proteins can occur due to promiscuous targeting sequences or pathway dysfunction, leading to cellular stress.
• TA proteins are subject to quality control mechanisms, including degradation pathways like TAD-C and TAD-M for resident proteins.

Purpose of the Study:

• To summarize and discuss the mechanisms of TA protein recognition, dislocation, and degradation.
• To highlight the role of the Msp1 AAA-ATPase in managing mistargeted and solitary TA proteins.
• To elucidate the Msp1 pathway's function at mitochondrial and peroxisomal membranes.

Main Methods:

• Review and synthesis of existing literature on TA protein targeting and quality control.
• Focus on the Msp1/ATAD1 AAA-ATPase and its interaction with mistargeted TA proteins.
• Examination of the subsequent ubiquitination and degradation steps involving the Doa10 E3 ligase complex.

Main Results:

• Msp1/ATAD1 directly recognizes and dislocates mistargeted and solitary TA proteins from mitochondrial and peroxisomal membranes.
• Dislocated TA proteins are ubiquitinated by the Doa10 E3 ligase complex for proteasomal degradation.
• This pathway provides a crucial quality control mechanism for aberrant TA proteins.

Conclusions:

• The Msp1 pathway is a key regulator of TA protein homeostasis, preventing the accumulation of mislocalized proteins.
• Understanding Msp1's substrate recognition and dislocation mechanisms is vital for comprehending cellular quality control.
• Dysfunction in the Msp1 pathway could have implications for various cellular processes and diseases.