The molecular mechanism of membrane protein complex assembly.

• Applicant: Dr. Tino Pleiner
• Subject Area: Biochemistry ; Cell Biology
• Term: from 2019 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 422880195

Virtually all cellular processes, from DNA replication to cell signaling, depend on multi-subunit protein complexes. Their assembly must be highly regulated to ensure generation of stoichiometrically defined, functional macromolecules. Any orphan subunits, that are synthesized in excess or remain unassembled, must be recognized and degraded by quality control machinery to prevent non-specific binding and cytotoxic aggregation. One class of proteins for which quaternary assembly poses a particular challenge is integral membrane proteins, which include hundreds of oligomeric ion channels, receptors, and transporters essential for cellular homeostasis. Many membrane protein subunits contain regions that, while necessary for function and oligomerization, would be thermodynamically unfavorable within the lipid bilayer. Very little is known about assembly factors that stabilize unassembled proteins in the ER membrane, or how these factors triage clients towards a biosynthetic or degradative fate. I propose to identify quality control factors that coordinate membrane protein assembly in mammals using two complementary strategies: in vitro biochemical analyses of the interactomes of orphan subunits and a genome-wide CRISPR/Cas9 knockout screen using a reporter cell line for membrane protein assembly. The identified candidates will be further analyzed using a combination of structural and functional strategies to examine the molecular mechanism of membrane protein complex assembly.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professorin Rebecca Voorhees