Research groupJunior group

Johannes Broichhagen


Portrait Johannes Broichhagen

Our lab is looking for new ways to visualize and interrogate biological function, such as cell signalling or protein dynamics.

Light up the invisible!

Putting the spotlight on the invisible to see more in research. Our expertise lies in the development of synthetic, custom-tailored fluorescent substrates to be used in microscopy. We think in and pursue unconventional ways in the design and synthesis of fluorophores for high-definition imaging in living cells.

Research Interests

Probes for compartmentalized labelling
In a dynamic cellular environment, proteins move and reside in different compartments. Accordingly, ways have to be found to label the same proteins differently when they are not at locations. Tuning the SNAP-tag substrate BG to its sulfonated version SBG, fluorophores are endowed with an impermeable leaving group. Besides better solubility, no evaluation of the cargo is needed as it stays untouched; and as such, any desired fluorophore can be employed to only label the surface exposed pool of a protein. Showcasing this for a member of every G protein-coupled receptor (GPCR) class, we performed super resolution microscopy, protein tracking of turnover and stoichiometry measurements of different receptor pools.  

Endogenous protein labelling
Attaching fluorophores to peptidic antagonists of GLP1R, a protein involved in glucose homeostasis and appetite regulation, we endowed this receptor in its native environment with a dye. As such, we are able to closely look where it resides in the cell, with ramifications for the understanding of protein dynamics and generation of specific markers for differentiated stem cells.

Photocontrolling GPCRs
G protein-coupled receptors are cell surface proteins that sense stimuli outside of the cell and translate this into an intracellular response. Albeit being the largest drug target, the activation mechanism and fine interplay remain partly understood. Using a combination of photoswitchable molecules with protein engineering, we are able to use light with its unique spatiotemporal resolution to remote- and precise-control metabotropic glutamate receptors, key players in health and disease in the nervous system. Recently, quantitative efficacy was achieved for the first time by increasing the valency of our photoswitches – a chemical trick that might be amenable to other targets.

Group Members


By PositionA-Z
  • After studying Chemistry in Erlangen with a one-year stint in the Weck group at NYU, JB graduated from the lab of Ivana Ivanovic-Burmazovic in 2010. Interested in biology, he joined the lab of Dirk Trauner at LMU Munich, obtaining his PhD in 2014 and pursuing his endeavours with Kai Johnsson, first at EPFL, then at the Max Planck for Medical Research in Heidelberg. He joined the FMP in 2020 as a Junior Group Leader in Chemical Biology.

  • Kilian studied chemistry at the Julius-Maximilian-University Würzburg (JMU) with focus on Organic, Physical and Medicinal Chemistry. For his Master Thesis he joined the group of Dirk Trauner at New York University (NYU), where he worked on photoswitchable PROTACs. After graduating in 2019, Kilian decided to join JB’s lab in 2020 to work on novel imaging techniques.

  • Ramona studied Biology with a focus on genetics and molecular biology at the Humboldt University Berlin, graduating 2010 in Molecular Ecology. After a stint at WITA GmbH, she joined the FMP as technical assistant in 2011, working in the field Molecular Cellular Physiology and Mass Spectrometry. Enjoying nature and being a passionate hiker in her free time, she teamed up with JB in 2020 to support and pursue our quests in Chemical Biology.