Origins and evolution of cotranslational transport to the ER

Area of Science:

• Molecular Biology
• Cell Biology
• Biochemistry

Background:

• Proteins function in diverse cellular locations but are synthesized in the cytosol.
• Translocating proteins across biological membranes is essential for all living organisms.
• The cotranslational transport pathway is the primary route for secretory and membrane proteins.

Purpose of the Study:

• To elucidate the fundamental mechanism of cotranslational protein transport.
• To explore the conserved and unique aspects of this pathway across different life forms.
• To investigate the regulatory circuitry and accessory components, particularly in eukaryotes.

Main Methods:

• Review of recent structural and biochemical studies.
• Analysis of conserved components across kingdoms of life.
• Focus on eukaryotic-specific accessory factors.

Main Results:

• The cotranslational transport pathway is a conserved, ancient system essential for protein localization.
• Key steps involve signal recognition particle (SRP) recognition, SRP-receptor mediated targeting, and translocation through a protein channel.
• Eukaryotic systems possess unique accessory components that offer insights into early eukaryotic evolution.

Conclusions:

• The core machinery for cotranslational protein translocation is highly conserved throughout evolution.
• Recent studies reveal intricate regulatory mechanisms and highlight eukaryotic-specific adaptations.
• Understanding these components sheds light on the evolution of cellular complexity.