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 PubMed
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.
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
- ↑ Shieh BH, Niemeyer B. A novel protein encoded by the InaD gene regulates recovery of visual transduction in Drosophila. Neuron. 1995 Jan;14(1):201-10. PMID:7826638
- ↑ Kumar R, Shieh BH. The second PDZ domain of INAD is a type I domain involved in binding to eye protein kinase C. Mutational analysis and naturally occurring variants. J Biol Chem. 2001 Jul 6;276(27):24971-7. Epub 2001 May 7. PMID:11342563 doi:http://dx.doi.org/10.1074/jbc.M103570200
- ↑ Mishra P, Socolich M, Wall MA, Graves J, Wang Z, Ranganathan R. Dynamic scaffolding in a G protein-coupled signaling system. Cell. 2007 Oct 5;131(1):80-92. PMID:17923089 doi:10.1016/j.cell.2007.07.037
