2qkt
From Proteopedia
Crystal Structure of the 5th PDZ domain of InaD
Structural highlights
Function[INAD_DROME] Involved in the negative feedback regulation of the light-activated signaling cascade in photoreceptors through a calcium-mediated process. Interacts with tetrapeptide ligand located in C-terminal sequence of 3 key components of the visual cascade, tethering them and forming a macromolecular signaling phototransduction complex.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThe 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. Dynamic scaffolding in a G protein-coupled signaling system.,Mishra P, Socolich M, Wall MA, Graves J, Wang Z, Ranganathan R Cell. 2007 Oct 5;131(1):80-92. PMID:17923089[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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