TY  - JOUR
A1  - Imam, Nasir
A1  - Choudhury, Susobhan
A1  - Heinze, Katrin G.
A1  - Schindelin, Hermann
T1  - Differential modulation of collybistin conformational dynamics by the closely related GTPases Cdc42 and TC10
JF  - Frontiers in Synaptic Neuroscience
N2  - Interneuronal synaptic transmission relies on the proper spatial organization of presynaptic neurotransmitter release and its reception on the postsynaptic side by cognate neurotransmitter receptors. Neurotransmitter receptors are incorporated into and arranged within the plasma membrane with the assistance of scaffolding and adaptor proteins. At inhibitory GABAergic postsynapses, collybistin, a neuronal adaptor protein, recruits the scaffolding protein gephyrin and interacts with various neuronal factors including cell adhesion proteins of the neuroligin family, the GABAA receptor α2-subunit and the closely related small GTPases Cdc42 and TC10 (RhoQ). Most collybistin splice variants harbor an N-terminal SH3 domain and exist in an autoinhibited/closed state. Cdc42 and TC10, despite sharing 67.4% amino acid sequence identity, interact differently with collybistin. Here, we delineate the molecular basis of the collybistin conformational activation induced by TC10 with the aid of recently developed collybistin FRET sensors. Time-resolved fluorescence-based FRET measurements reveal that TC10 binds to closed/inactive collybistin leading to relief of its autoinhibition, contrary to Cdc42, which only interacts with collybistin when forced into an open state by the introduction of mutations destabilizing the closed state of collybistin. Taken together, our data describe a TC10-driven signaling mechanism in which collybistin switches from its autoinhibited closed state to an open/active state.
KW  - autoinhibition
KW  - fluorescence resonance energy transfer (FRET)
KW  - gephyrin
KW  - guanine nucleotide exchange factor (GEF)
KW  - inhibitory postsynapse
KW  - Rho GTPase
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-282816
SN  - 1663-3563
VL  - 14
ER  - 
TY  - JOUR
A1  - Balakrishnan, Ashwin
A1  - Hemmen, Katherina
A1  - Choudhury, Susobhan
A1  - Krohn, Jan-Hagen
A1  - Jansen, Kerstin
A1  - Friedrich, Mike
A1  - Beliu, Gerti
A1  - Sauer, Markus
A1  - Lohse, Martin J.
A1  - Heinze, Katrin G.
T1  - Unraveling the hidden temporal range of fast β2-adrenergic receptor mobility by time-resolved fluorescence
JF  - Communications Biology
N2  - G-protein-coupled receptors (GPCRs) are hypothesized to possess molecular mobility over a wide temporal range. Until now the temporal range has not been fully accessible due to the crucially limited temporal range of available methods. This in turn, may lead relevant dynamic constants to remain masked. Here, we expand this dynamic range by combining fluorescent techniques using a spot confocal setup. We decipher mobility constants of β\(_{2}\)-adrenergic receptor over a wide time range (nanosecond to second). Particularly, a translational mobility (10 µm\(^{2}\)/s), one order of magnitude faster than membrane associated lateral mobility that explains membrane protein turnover and suggests a wider picture of the GPCR availability on the plasma membrane. And a so far elusive rotational mobility (1-200 µs) which depicts a previously overlooked dynamic component that, despite all complexity, behaves largely as predicted by the Saffman-Delbrück model.
KW  - G-protein-coupled receptors
KW  - molecular mobility
KW  - temporal range
Y1  - 2022
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-301140
VL  - 5
IS  - 1
ER  -