NIH Proteomics Interest Group

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ProtIG is an NIH Special Interest Group (SIG) that organizes seminars and workshops in relevant areas of proteomics, including talks on separation and protein identification methods, determination of post-translational modifications, protein-protein interactions, and bioinformatics and data management. A monthly seminar series is usually held at 11am on the first Wednesday of each month (always check the Mtgs/Seminars button on this page for these and other PROTIG announced meetings). To receive email announcements of ProtIG events, join the listserv (Join the SIG button on this page)

January ProtIG Seminar
Please note the time and location
January 4th, 2018
9:30 am - 10:30am
Building 50, NIH Campus
Room 1227/1233 (Front Conference Room)
Vivek Mahadevan, Ph.D
Visiting Scientist
Section on Cellular and Synaptic Physiology
National Institute of Child Health & Human Development<

"Native KCC2 interactome reveals PACSIN1 as a critical regulator of synaptic inhibition"

KCC2 is a neuron-specific K+-Cl- cotransporter essential for establishing the Cl- gradient required for fast hyperpolarizing GABAergic and glycinergic inhibition. KCC2 is highly localized to excitatory synapses where it regulates spine morphogenesis and AMPA receptor confinement. Aberrant KCC2 function contributes to numerous human neurological disorders including epilepsy, neuropathic pain, schizophrenia and autism spectrum disorders. In the present study, we performed unbiased affinity purifications of native-KCC2 coupled with high-resolution mass spectrometry using three different KCC2 epitopes from whole-brain membrane fractions prepared from developing (P5) and mature mouse brain (P50).

We determined that the mouse brain KCC2 functional interactome is comprised of 181 proteins belonging to diverse classes of transmembrane and soluble proteins; and by mapping the KCC2 interactome to excitatory and inhibitory synapse proteomes and performing ingenuity pathway analysis, we determined that KCC2 partners are highly enriched at excitatory synapses and form a dense network with proteins involved in receptor trafficking. Notably, this analysis revealed multiple novel putative-KCC2 partners, including PACSIN1, SNAP25, RAB11FIP5, CSNK2A1, DNM1 and AP2B1. All of these novel putative interactors have established functions in membrane recycling and/or trafficking of distinct glutamate receptor subunits.

The most abundant KCC2 interactor is a neuronal endocytic regulatory protein termed PACSIN1 (SYNDAPIN1). We verified the PACSIN1-KCC2 interaction biochemically and demonstrated that shRNA knockdown of PACSIN1 in hippocampal neurons significantly increases KCC2 expression and hyperpolarizes the reversal potential for Cl-. Overall, our global native-KCC2 interactome and subsequent characterization revealed PACSIN1 as a novel and potent negative regulator of KCC2.

In conclusion, the KCC2 interactome as presented here, serves as a molecular framework for systematically exploring how KCC2 up and down states can be dynamically regulated by its native molecular constituents, thereby providing a blueprint for subsequent detailed functional investigations.

Seminars will be webcast online at and available on the
Proteomics Interest Group website as an archived presentation unless otherwise noted.

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This site was updated on December 28th, 2017. Please contact Renee Olano at olanol(at) with questions or suggestions.