@article{8988,
  abstract     = {The differentiation of cells depends on a precise control of their internal organization, which is the result of a complex dynamic interplay between the cytoskeleton, molecular motors, signaling molecules, and membranes. For example, in the developing neuron, the protein ADAP1 (ADP-ribosylation factor GTPase-activating protein [ArfGAP] with dual pleckstrin homology [PH] domains 1) has been suggested to control dendrite branching by regulating the small GTPase ARF6. Together with the motor protein KIF13B, ADAP1 is also thought to mediate delivery of the second messenger phosphatidylinositol (3,4,5)-trisphosphate (PIP3) to the axon tip, thus contributing to PIP3 polarity. However, what defines the function of ADAP1 and how its different roles are coordinated are still not clear. Here, we studied ADAP1’s functions using in vitro reconstitutions. We found that KIF13B transports ADAP1 along microtubules, but that PIP3 as well as PI(3,4)P2 act as stop signals for this transport instead of being transported. We also demonstrate that these phosphoinositides activate ADAP1’s enzymatic activity to catalyze GTP hydrolysis by ARF6. Together, our results support a model for the cellular function of ADAP1, where KIF13B transports ADAP1 until it encounters high PIP3/PI(3,4)P2 concentrations in the plasma membrane. Here, ADAP1 disassociates from the motor to inactivate ARF6, promoting dendrite branching.},
  author       = {Düllberg, Christian F and Auer, Albert and Canigova, Nikola and Loibl, Katrin and Loose, Martin},
  issn         = {10916490},
  journal      = {PNAS},
  number       = {1},
  publisher    = {National Academy of Sciences},
  title        = {{In vitro reconstitution reveals phosphoinositides as cargo-release factors and activators of the ARF6 GAP ADAP1}},
  doi          = {10.1073/pnas.2010054118},
  volume       = {118},
  year         = {2021},
}

@article{7580,
  abstract     = {The eukaryotic endomembrane system is controlled by small GTPases of the Rab family, which are activated at defined times and locations in a switch-like manner. While this switch is well understood for an individual protein, how regulatory networks produce intracellular activity patterns is currently not known. Here, we combine in vitro reconstitution experiments with computational modeling to study a minimal Rab5 activation network. We find that the molecular interactions in this system give rise to a positive feedback and bistable collective switching of Rab5. Furthermore, we find that switching near the critical point is intrinsically stochastic and provide evidence that controlling the inactive population of Rab5 on the membrane can shape the network response. Notably, we demonstrate that collective switching can spread on the membrane surface as a traveling wave of Rab5 activation. Together, our findings reveal how biochemical signaling networks control vesicle trafficking pathways and how their nonequilibrium properties define the spatiotemporal organization of the cell.},
  author       = {Bezeljak, Urban and Loya, Hrushikesh and Kaczmarek, Beata M and Saunders, Timothy E. and Loose, Martin},
  issn         = {1091-6490},
  journal      = {Proceedings of the National Academy of Sciences},
  number       = {12},
  pages        = {6504--6549},
  publisher    = {Proceedings of the National Academy of Sciences},
  title        = {{Stochastic activation and bistability in a Rab GTPase regulatory network}},
  doi          = {10.1073/pnas.1921027117},
  volume       = {117},
  year         = {2020},
}