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Séminaire impromptu - Kenneth Lindegaard MadsenHow protein-membrane interactions regulate scaffold and trafficking processes.

Abstract :


 Our group has developed around the understanding of the intricate interplay of protein-protein and protein-membrane interaction
in processes relating to cellular scaffold and trafficking processes – and in particular how amphipathic helices inserting into the lipid membrane may shape these processes.

First part of the talk will address assembly of PDZ scaffolds using supported cell membrane sheets, a unique experimental setup enabling direct access to the intracellular face of the cell membrane. Our data demonstrate how multivalent protein-protein and protein-lipid interactions provide critical avidity for the strong binding between the PDZ domain scaffold proteins, PICK1 and PSD-95, and their cognate transmembrane binding partners. The kinetics of the binding were remarkably slow and binding strength two-three orders of magnitude higher than the intrinsic affinity for the isolated PDZ interaction. Interestingly, discrete changes in the intrinsic PICK1 PDZ affinity did not affect overall binding strength but instead revealed dual scaffold modes for PICK1.

Second part, with focus on helix 8 in class A GPCRs, will address ongoing investigations of the ability of amphipathic helices in transmembrane protein to autonomously drive constitutive internalization through insertion in the plasma membrane. This insertion seems to drive a novel route of internalization and engages also the transferrin receptor in trans, suggesting that GPCRs, to a large extent, shape their own destiny in trafficking processes.


 

Selected publications

Erlendsson, S. and Madsen, K.L. Membrane binding and modulation of the PDZ domain of PICK1 Membranes 5(4), 597-615 doi:10.3390/membranes5040597 (2015) I.F. not available

Karlsen, M.L., Thorsen, T.S., Johner, N., Ammendrup-Johnsen, I., Erlendsson, S., Tian, X., Simonsen, J.B., Høiberg-Nielsen, R., Christensen, N.M., Khelashvili, G., Streicher, W., Teilum, K., Vestergaard, B., Weinstein, H., Gether, U., Arleth, L. and Madsen, K.L. Structure of Dimeric and Tetrameric Complexes of the BAR Domain Protein PICK1 Determined by Small-Angle X-Ray Scattering. Structure. 23(7):1258-70. doi:10.1016/j.str.2015.04.020 (2015)

Rathje, M., Fang, H., Bachman, J.L., Gether, U., Huganir, R.L., Madsen, K.L. Reply to Wilkinson et al.: Concerning the use of pHluorin-tagged GluA2 as a reporter for NMDA-induced AMPA receptor recycling. Proceedings of the National Academy of Sciences USA 111, E305-E305, doi:10.1073/pnas.1320452111 (2014)