PDZ is an acronym derived from the names of the first proteins in which the domain was observed. Post-synaptic density protein 95 (PSD-95) is a synaptic protein found only in the brain. Drosophila disc large tumor suppressor (Dlg1) and zona occludens 1 (ZO-1) both play an important role at cell junctions and in cell signaling complexes. Since the discovery of PDZ domains more than 20 years ago, hundreds of additional PDZ domains have been identified. The first published use of the phrase “PDZ domain” was not in a paper, but a letter. In September 1995, Dr. Mary B. Kennedy of the California Institute of Technology wrote a letter of correction to Trends in Biomedical Sciences. Earlier that year, another set of scientists had claimed to discover a new protein domain which they called a DHR domain. Dr. Kennedy refuted that her lab had previously described exactly the same domain as a series of “GLGF repeats”. She continued to explain that in order to “better reflect the origin and distribution of the domain,” the new title of the domain would be changed. Thus, the name “PDZ domain” was introduced to the world.
PDZ domain structure is partially conserved across the various proteins that contain them. They usually have 5-6 β-strands and one short and one long α-helix. Apart from this conserved fold, the secondary structure differs across PDZ domains. This domain tends to be globular with a diameter of about 35 Å.
PDZ domains have two main functions: Localizing cellular elements, and regulating cellular pathways.
The first discovered function of the PDZ domains was to anchor receptor proteins in the membrane to cytoskeletal components. PDZ domains also have regulatory functions on different signaling pathways. Any protein may have one or several PDZ domains, which can be identical or unique (see figure to right). This variety allows these proteins to be very versatile in their interactions. Different PDZ domains in the same protein can have different roles, each binding a different part of the target protein or a different protein altogether.
PDZ domains play a vital role in organizing and maintaining complex scaffolding formations.
PDZ domains are found in diverse proteins, but all assist in localization of cellular elements. PDZ domains are primarily involved in anchoring receptor proteins to the cytoskeleton. For cells to function properly it is important for components—proteins and other molecules— to be in the right place at the right time. Proteins with PDZ domains bind different components to ensure correct arrangements. In the neuron, making sense of neurotransmitter activity requires specific receptors to be located in the lipid membrane at the synapse. PDZ domains are crucial to this receptor localization process. Proteins with PDZ domains generally associate with both the C-terminus of the receptor and cytoskeletal elements in order to anchor the receptor to the cytoskeleton and keep it in place. Without such an interaction, receptors would diffuse out of the synapse due to the fluid nature of the lipid membrane.
PDZ domains are also utilized to localize elements other than receptor proteins. In the human brain, nitric oxide often acts in the synapse to modify cGMP levels in response to NMDA receptor activation. In order to ensure a favorable spatial arrangements, neuronal nitric oxide synthase (nNOS) is brought close to NMDA receptors via interactions with PDZ domains on PSD-95, which concurrently binds nNOS and NMDA receptors. With nNOS located closely to NMDA receptors, it will be activated immediately after calcium ions begin entering the cell.
PDZ domains are directly involved in the regulation of different cellular pathways. This mechanism of this regulation varies as PDZ domains are able to interact with a range of cellular components. This regulation is usually a result of the co-localization of multiple signaling molecules such as in the example with nNos and NMDA receptors. Some examples of signaling pathway regulation executed by the PDZ domain include phosphatase enzyme activity, mechanosensory signaling, and the sorting pathway of endocytosed receptor proteins.
PDZ domains are being studied further to better understand the role they play in different signaling pathways. Research has increased as these domains have been linked to different diseases including cancer as discussed above.
PDZ domain function can be both inhibited and activated by various mechanisms. Two of the most prevalent include allosteric interactions and posttranslational modifications.
Another post-translational modification that can regulate PDZ domains is the formation of disulfide bridges. Many PDZ domains contain cysteines and are susceptible to disulfide bond formation in oxidizing conditions. This modification acts primarily as an inhibitor of PDZ domain function.
PDZ proteins are a family of proteins that contain the PDZ domain. This sequence of amino-acids is found in many thousands of known proteins. PDZ domain proteins are widespread in eukaryotes and eubacteria, whereas there are very few examples of the protein in archaea. PDZ domains are often associated with other protein domains and these combinations allow them to carry out their specific functions. Three of the most well documented PDZ proteins are PSD-95, GRIP, and HOMER.
PSD-95 is a brain synaptic protein with three PDZ domains, each with unique properties and structures that allow PSD-95 to function in many ways. In general, the first two PDZ domains interact with receptors and the third interacts with cytoskeleton-related proteins. The main receptors associated with PSD-95 are NMDA receptors. The first two PDZ domains of PSD-95 bind to the C-terminus of NMDA receptors and anchor them in the membrane at the point of neurotransmitter release. The first two PDZ domains can also interact in a similar fashion with Shaker-type K+ channels. A PDZ interaction between PSD-95, nNOS and syntrophin is mediated by the second PDZ domain. The third and final PDZ domain links to cysteine-rich PDZ-binding protein (CRIPT), which allows PSD-95 to associate with the cytoskeleton.
There are roughly 260 PDZ domains in humans. Several proteins contain multiple PDZ domains, so the number of unique PDZ-containing proteins is closer to 180. In the table below are some of the better studied members of this family:
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Lee HJ, Zheng JJ (May 2010). "PDZ domains and their binding partners: structure, specificity, and modification". Cell Communication and Signaling. 8: 8. doi:10.1186/1478-811X-8-8. PMC 2891790. PMID 20509869. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891790
Li J, Callaway DJ, Bu Z (September 2009). "Ezrin induces long-range interdomain allostery in the scaffolding protein NHERF1". Journal of Molecular Biology. 392 (1): 166–80. doi:10.1016/j.jmb.2009.07.005. PMC 2756645. PMID 19591839. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756645
Kennedy MB (September 1995). "Origin of PDZ (DHR, GLGF) domains". Trends in Biochemical Sciences. 20 (9): 350. doi:10.1016/S0968-0004(00)89074-X. PMID 7482701. /wiki/Mary_B._Kennedy
Ponting CP, Phillips C (March 1995). "DHR domains in syntrophins, neuronal NO synthases and other intracellular proteins". Trends in Biochemical Sciences. 20 (3): 102–3. doi:10.1016/S0968-0004(00)88973-2. PMID 7535955. /wiki/Doi_(identifier)
Cho KO, Hunt CA, Kennedy MB (November 1992). "The rat brain postsynaptic density fraction contains a homolog of the Drosophila discs-large tumor suppressor protein". Neuron. 9 (5): 929–42. doi:10.1016/0896-6273(92)90245-9. PMID 1419001. S2CID 28528759. /wiki/Doi_(identifier)
Cowburn D (December 1997). "Peptide recognition by PTB and PDZ domains". Current Opinion in Structural Biology. 7 (6): 835–8. doi:10.1016/S0959-440X(97)80155-8. PMID 9434904. /wiki/Doi_(identifier)
Cho KO, Hunt CA, Kennedy MB (November 1992). "The rat brain postsynaptic density fraction contains a homolog of the Drosophila discs-large tumor suppressor protein". Neuron. 9 (5): 929–42. doi:10.1016/0896-6273(92)90245-9. PMID 1419001. S2CID 28528759. /wiki/Doi_(identifier)
Liu J, Li J, Ren Y, Liu P (2014-01-01). "DLG5 in cell polarity maintenance and cancer development". International Journal of Biological Sciences. 10 (5): 543–9. doi:10.7150/ijbs.8888. PMC 4046881. PMID 24910533. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4046881
Kennedy MB (September 1995). "Origin of PDZ (DHR, GLGF) domains". Trends in Biochemical Sciences. 20 (9): 350. doi:10.1016/s0968-0004(00)89074-x. PMID 7482701. /wiki/Doi_(identifier)
Ponting CP, Phillips C (March 1995). "DHR domains in syntrophins, neuronal NO synthases and other intracellular proteins". Trends in Biochemical Sciences. 20 (3): 102–3. doi:10.1016/S0968-0004(00)88973-2. PMID 7535955. /wiki/Doi_(identifier)
Cho KO, Hunt CA, Kennedy MB (November 1992). "The rat brain postsynaptic density fraction contains a homolog of the Drosophila discs-large tumor suppressor protein". Neuron. 9 (5): 929–42. doi:10.1016/0896-6273(92)90245-9. PMID 1419001. S2CID 28528759. /wiki/Doi_(identifier)
Lee HJ, Zheng JJ (May 2010). "PDZ domains and their binding partners: structure, specificity, and modification". Cell Communication and Signaling. 8: 8. doi:10.1186/1478-811X-8-8. PMC 2891790. PMID 20509869. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891790
Erlendsson S, Madsen KL (October 2015). "Membrane Binding and Modulation of the PDZ Domain of PICK1". Membranes. 5 (4): 597–615. doi:10.3390/membranes5040597. PMC 4704001. PMID 26501328. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4704001
Lee HJ, Zheng JJ (May 2010). "PDZ domains and their binding partners: structure, specificity, and modification". Cell Communication and Signaling. 8: 8. doi:10.1186/1478-811X-8-8. PMC 2891790. PMID 20509869. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891790
Morais Cabral JH, Petosa C, Sutcliffe MJ, Raza S, Byron O, Poy F, et al. (August 1996). "Crystal structure of a PDZ domain". Nature. 382 (6592): 649–52. Bibcode:1996Natur.382..649C. doi:10.1038/382649a0. PMID 8757139. S2CID 4344406. /wiki/Bibcode_(identifier)
Harris BZ, Lim WA (September 2001). "Mechanism and role of PDZ domains in signaling complex assembly". Journal of Cell Science. 114 (Pt 18): 3219–31. doi:10.1242/jcs.114.18.3219. PMID 11591811. /wiki/Doi_(identifier)
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Harris BZ, Lim WA (September 2001). "Mechanism and role of PDZ domains in signaling complex assembly". Journal of Cell Science. 114 (Pt 18): 3219–31. doi:10.1242/jcs.114.18.3219. PMID 11591811. /wiki/Doi_(identifier)
Brakeman PR, Lanahan AA, O'Brien R, Roche K, Barnes CA, Huganir RL, Worley PF (March 1997). "Homer: a protein that selectively binds metabotropic glutamate receptors". Nature. 386 (6622): 284–8. Bibcode:1997Natur.386..284B. doi:10.1038/386284a0. PMID 9069287. S2CID 4346579. /wiki/Bibcode_(identifier)
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Doyle DA, Lee A, Lewis J, Kim E, Sheng M, MacKinnon R (June 1996). "Crystal structures of a complexed and peptide-free membrane protein-binding domain: molecular basis of peptide recognition by PDZ". Cell. 85 (7): 1067–76. doi:10.1016/S0092-8674(00)81307-0. PMID 8674113. S2CID 9739481. /wiki/Eunjoon_Kim
Hopper R, Lancaster B, Garthwaite J (April 2004). "On the regulation of NMDA receptors by nitric oxide". The European Journal of Neuroscience. 19 (7): 1675–82. doi:10.1111/j.1460-9568.2004.03306.x. PMID 15078541. S2CID 23939649. /wiki/Doi_(identifier)
Doyle DA, Lee A, Lewis J, Kim E, Sheng M, MacKinnon R (June 1996). "Crystal structures of a complexed and peptide-free membrane protein-binding domain: molecular basis of peptide recognition by PDZ". Cell. 85 (7): 1067–76. doi:10.1016/S0092-8674(00)81307-0. PMID 8674113. S2CID 9739481. /wiki/Eunjoon_Kim
Doyle DA, Lee A, Lewis J, Kim E, Sheng M, MacKinnon R (June 1996). "Crystal structures of a complexed and peptide-free membrane protein-binding domain: molecular basis of peptide recognition by PDZ". Cell. 85 (7): 1067–76. doi:10.1016/S0092-8674(00)81307-0. PMID 8674113. S2CID 9739481. /wiki/Eunjoon_Kim
Maisonneuve P, Caillet-Saguy C, Raynal B, Gilquin B, Chaffotte A, Pérez J, et al. (November 2014). "Regulation of the catalytic activity of the human phosphatase PTPN4 by its PDZ domain". The FEBS Journal. 281 (21): 4852–65. doi:10.1111/febs.13024. PMID 25158884. S2CID 205135373. /wiki/Doi_(identifier)
de Nooij JC, Simon CM, Simon A, Doobar S, Steel KP, Banks RW, et al. (February 2015). "The PDZ-domain protein Whirlin facilitates mechanosensory signaling in mammalian proprioceptors". The Journal of Neuroscience. 35 (7): 3073–84. doi:10.1523/JNEUROSCI.3699-14.2015. PMC 4331628. PMID 25698744. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331628
Cao TT, Deacon HW, Reczek D, Bretscher A, von Zastrow M (September 1999). "A kinase-regulated PDZ-domain interaction controls endocytic sorting of the beta2-adrenergic receptor". Nature. 401 (6750): 286–90. Bibcode:1999Natur.401..286C. doi:10.1038/45816. PMID 10499588. S2CID 4386883. /wiki/Bibcode_(identifier)
Wang NX, Lee HJ, Zheng JJ (April 2008). "Therapeutic use of PDZ protein-protein interaction antagonism". Drug News & Perspectives. 21 (3): 137–41. doi:10.1358/dnp.2008.21.3.1203409. PMC 4055467. PMID 18560611. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4055467
Lee HJ, Zheng JJ (May 2010). "PDZ domains and their binding partners: structure, specificity, and modification". Cell Communication and Signaling. 8: 8. doi:10.1186/1478-811X-8-8. PMC 2891790. PMID 20509869. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2891790
Chung HJ, Huang YH, Lau LF, Huganir RL (November 2004). "Regulation of the NMDA receptor complex and trafficking by activity-dependent phosphorylation of the NR2B subunit PDZ ligand". The Journal of Neuroscience. 24 (45): 10248–59. doi:10.1523/JNEUROSCI.0546-04.2004. PMC 6730169. PMID 15537897. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6730169
Jeleń F, Oleksy A, Smietana K, Otlewski J (2003-01-01). "PDZ domains - common players in the cell signaling". Acta Biochimica Polonica. 50 (4): 985–1017. doi:10.18388/abp.2003_3628. PMID 14739991. https://doi.org/10.18388%2Fabp.2003_3628
Chen J, Pan L, Wei Z, Zhao Y, Zhang M (August 2008). "Domain-swapped dimerization of ZO-1 PDZ2 generates specific and regulatory connexin43-binding sites". The EMBO Journal. 27 (15): 2113–23. doi:10.1038/emboj.2008.138. PMC 2516886. PMID 18636092. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2516886
Chen BS, Braud S, Badger JD, Isaac JT, Roche KW (June 2006). "Regulation of NR1/NR2C N-methyl-D-aspartate (NMDA) receptors by phosphorylation". The Journal of Biological Chemistry. 281 (24): 16583–90. doi:10.1074/jbc.M513029200. PMID 16606616. https://doi.org/10.1074%2Fjbc.M513029200
Mishra P, Socolich M, Wall MA, Graves J, Wang Z, Ranganathan R (October 2007). "Dynamic scaffolding in a G protein-coupled signaling system". Cell. 131 (1): 80–92. doi:10.1016/j.cell.2007.07.037. PMID 17923089. S2CID 14008319. https://doi.org/10.1016%2Fj.cell.2007.07.037
van den Berk LC, Landi E, Walma T, Vuister GW, Dente L, Hendriks WJ (November 2007). "An allosteric intramolecular PDZ-PDZ interaction modulates PTP-BL PDZ2 binding specificity". Biochemistry. 46 (47): 13629–37. doi:10.1021/bi700954e. PMID 17979300. /wiki/Doi_(identifier)
Li J, Callaway DJ, Bu Z (September 2009). "Ezrin induces long-range interdomain allostery in the scaffolding protein NHERF1". Journal of Molecular Biology. 392 (1): 166–80. doi:10.1016/j.jmb.2009.07.005. PMC 2756645. PMID 19591839. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2756645
Ponting CP (February 1997). "Evidence for PDZ domains in bacteria, yeast, and plants". Protein Science. 6 (2): 464–8. doi:10.1002/pro.5560060225. PMC 2143646. PMID 9041651. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2143646
Niethammer M, Valtschanoff JG, Kapoor TM, Allison DW, Weinberg RJ, Craig AM, Sheng M (April 1998). "CRIPT, a novel postsynaptic protein that binds to the third PDZ domain of PSD-95/SAP90". Neuron. 20 (4): 693–707. doi:10.1016/s0896-6273(00)81009-0. PMID 9581762. S2CID 16068361. https://doi.org/10.1016%2Fs0896-6273%2800%2981009-0
Niethammer M, Valtschanoff JG, Kapoor TM, Allison DW, Weinberg RJ, Craig AM, Sheng M (April 1998). "CRIPT, a novel postsynaptic protein that binds to the third PDZ domain of PSD-95/SAP90". Neuron. 20 (4): 693–707. doi:10.1016/s0896-6273(00)81009-0. PMID 9581762. S2CID 16068361. https://doi.org/10.1016%2Fs0896-6273%2800%2981009-0
Niethammer M, Valtschanoff JG, Kapoor TM, Allison DW, Weinberg RJ, Craig AM, Sheng M (April 1998). "CRIPT, a novel postsynaptic protein that binds to the third PDZ domain of PSD-95/SAP90". Neuron. 20 (4): 693–707. doi:10.1016/s0896-6273(00)81009-0. PMID 9581762. S2CID 16068361. https://doi.org/10.1016%2Fs0896-6273%2800%2981009-0
Dong H, O'Brien RJ, Fung ET, Lanahan AA, Worley PF, Huganir RL (March 1997). "GRIP: a synaptic PDZ domain-containing protein that interacts with AMPA receptors". Nature. 386 (6622): 279–84. Bibcode:1997Natur.386..279D. doi:10.1038/386279a0. PMID 9069286. S2CID 4361791. /wiki/Bibcode_(identifier)
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Torres R, Firestein BL, Dong H, Staudinger J, Olson EN, Huganir RL, et al. (December 1998). "PDZ proteins bind, cluster, and synaptically colocalize with Eph receptors and their ephrin ligands". Neuron. 21 (6): 1453–63. doi:10.1016/S0896-6273(00)80663-7. PMID 9883737. S2CID 15441813. https://doi.org/10.1016%2FS0896-6273%2800%2980663-7
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Brakeman PR, Lanahan AA, O'Brien R, Roche K, Barnes CA, Huganir RL, Worley PF (March 1997). "Homer: a protein that selectively binds metabotropic glutamate receptors". Nature. 386 (6622): 284–8. Bibcode:1997Natur.386..284B. doi:10.1038/386284a0. PMID 9069287. S2CID 4346579. /wiki/Bibcode_(identifier)
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