Advances in Combinatorial Chemistry & High Throughput Screening

A Homogeneous Platform to Discover Inhibitors of the GoLoco Motif/G-alpha Interaction

Author(s): Adam J. Kimple, Adam Yasgar, Mark Hughes, Ajit Jadhav, Francis S. Willard, Robin E. Muller, Christopher P. Austin, James Inglese, Gordon C. Ibeanu, David P. Siderovski and Anton Simeonov

Pp: 187-218 (32)

DOI: 10.2174/9781608057450113010010

* (Excluding Mailing and Handling)

Abstract

The GoLoco motif is a short Gα-binding polypeptide sequence. It is often found in proteins that regulate cell-surface receptor signaling, such as RGS12, as well as in proteins that regulate mitotic spindle orientation and force generation during cell division, such as GPSM2/LGN. Here, we describe a high-throughput fluorescence polarization (FP) assay using fluorophore-labeled GoLoco motif peptides for identifying inhibitors of the GoLoco motif interaction with the G-protein alpha subunit Gαi1. The assay exhibits considerable stability over time and is tolerant to DMSO up to 5%. The Z´-factors for robustness of the GPSM2 and RGS12 GoLoco motif assays in a 96-well plate format were determined to be 0.81 and 0.84, respectively; the latter assay was run in a 384-well plate format and produced a Z´-factor of 0.80. To determine the screening factor window (Zfactor) of the RGS12 GoLoco motif screen using a small molecule library, the NCI Diversity Set was screened. The Z-factor was determined to be 0.66, suggesting that this FP assay would perform well when developed for 1,536-well format and scaled up to larger libraries. We then miniaturized to a 4 μL final volume a pair of FP assays utilizing fluorescein- (green) and rhodamine- (red) labeled RGS12 GoLoco motif peptides. In a fully-automated run, the Sigma-Aldrich LOPAC1280 collection was screened three times with every library compound being tested over a range of concentrations following the quantitative highthroughput screening (qHTS) paradigm; excellent assay performance was noted with average Z-factors of 0.84 and 0.66 for the green- and red-label assays, respectively.


Keywords: Fluorescence anisotropy, fluorescence polarization, GoLoco motif, heterotrimeric G-proteins, high-throughput screening.

Related Journals
Related Books
© 2024 Bentham Science Publishers | Privacy Policy