Jodok Ritz

Master student. U172

Directed membrane protein degradation in cell-mimicking in vitro systems

Membrane proteins are involved in a wide variety of cellular processes, so their investigation is crucial to understand how cells function. Inconveniently, the hydrophobic properties of the membrane proteins impede the structural and functional characterisation. Usually they are extracted with detergents, purified and integrated into systems which mimic their natural environment in a membrane. A powerful method is the reconstitution into small lipid vesicles called liposomes that allow for measurements of transmembrane substrate transport.[1,2]

An important aspect of this reconstitution is the orientation of the membrane proteins. There are two different ways a membrane protein can be embedded into the liposomal membrane, right-side out or inside out. However, it is hard to influence orientation in vitro and often liposomes contain many copies of a protein in random orientations. This can lead to heterogeneity in the experimental system and strongly affect functional studies.[1,3] The aim of the project is thus to implement a new route to selectively degrade membrane proteins reconstituted in the undesired orientation.


  1. Amati A.M., Graf S., Deutschmann S., Dolder N., von Ballmoos C. (2020) Current problems and future avenues in proteoliposome research. Biochem Soc Trans. 2020 Aug, doi: 10.1042/BST20190966
  2. Rawlings AE. (2016) Membrane proteins: always an insoluble problem? Biochem Soc Trans., 15;44(3):790-5. doi: 10.1042/BST20160025
  3. Deutschmann S., Rimle L., von Ballmoos C. (2021) Rapid estimation of membrane protein orientation in liposomes. ChemBioChem. 2021 Nov, doi: 10.1002/cbic.202100543