2QKT

Crystal Structure of the 5th PDZ domain of InaD

Summary for 2QKT

• Entry DOI: 10.2210/pdb2qkt/pdb
• Descriptor: Inactivation-no-after-potential D protein (2 entities in total)
• Functional Keywords: pdz domain, scaffolding protein, disulfide-bond, membrane, sensory transduction, vision, signaling protein, peptide binding protein
• Biological source: Drosophila melanogaster (fruit fly)
• Cellular location: Cell membrane; Peripheral membrane protein: Q24008
• Total number of polymer chains: 2
• Total formula weight: 19422.40

Authors

Ranganathan, R.,Socolich, M. (deposition date: 2007-07-11, release date: 2007-11-06, Last modification date: 2024-10-30)

Primary citation

Mishra, P.,Socolich, M.,Wall, M.A.,Graves, J.,Wang, Z.,Ranganathan, R.
Dynamic Scaffolding in a G Protein-Coupled Signaling System.
Cell(Cambridge,Mass.), 131:80-92, 2007

PubMed Abstract: The INAD scaffold organizes a multiprotein complex that is essential for proper visual signaling in Drosophila photoreceptor cells. Here we show that one of the INAD PDZ domains (PDZ5) exists in a redox-dependent equilibrium between two conformations--a reduced form that is similar to the structure of other PDZ domains, and an oxidized form in which the ligand-binding site is distorted through formation of a strong intramolecular disulfide bond. We demonstrate transient light-dependent formation of this disulfide bond in vivo and find that transgenic flies expressing a mutant INAD in which PDZ5 is locked in the reduced state display severe defects in termination of visual responses and visually mediated reflex behavior. These studies demonstrate a conformational switch mechanism for PDZ domain function and suggest that INAD behaves more like a dynamic machine rather than a passive scaffold, regulating signal transduction at the millisecond timescale through cycles of conformational change.

PubMed: 17923089
DOI: 10.1016/j.cell.2007.07.037

Experimental method

X-RAY DIFFRACTION (2.05 Å)