Resistance to inhibitors of cholinesterase 8A (Ric8A) is an essential regulator of G protein α-subunits (Gα), acting as a guanine nucleotide exchange factor and a chaperone. We report two crystal structures of Ric8A, one in the apo form and the other ...
Resistance to inhibitors of cholinesterase 8A (Ric8A) is an essential regulator of G protein α-subunits (Gα), acting as a guanine nucleotide exchange factor and a chaperone. We report two crystal structures of Ric8A, one in the apo form and the other in complex with a tagged C-terminal fragment of Gα. These structures reveal two principal domains of Ric8A: an armadillo-fold core and a flexible C-terminal tail. Additionally, they show that the Gα C-terminus binds to a highly-conserved patch on the concave surface of the Ric8A armadillo-domain, with selectivity determinants residing in the Gα sequence. Biochemical analysis shows that the Ric8A C-terminal tail is critical for its stability and function. A model of the Ric8A/Gα complex derived from crosslinking mass spectrometry and molecular dynamics simulations suggests that the Ric8A C-terminal tail helps organize the GTP-binding site of Gα. This study lays the groundwork for understanding Ric8A function at the molecular level.
Organizational Affiliation:
Department of Biochemistry, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.,Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA. nikolai-artemyev@uiowa.edu.,Department of Molecular Physiology and Biophysics, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.,Protein Crystallography Facility, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA.,Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, IA, 52242, USA. nikolai-artemyev@uiowa.edu.
Download Mendeley
Download Endnote
