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8.A.24 The Ezrin/Radixin/Moesin-binding Phosphoprotein 50 (EBP50) Family

EBP50 is a Na+/H+ exchange regulatory cofactor, called NHE-RF or NHERF-1, of 358 aas (Slc9 isoform A3, regulatory factor 3). It is an adaptor protein that organizes a number of cell receptors and channels (Li et al., 2005). It contains two PDZ domains that bind to the cytoplasmic domains of a number of membrane channels, carriers and receptors to coordinate the assembly and trafficking of these transmembrane proteins. Most target proteins harboring a C-terminus recognition motif bind more-or-less equivalently to either of the PDZ domains, which contain identical core-binding motifs. However some substrates such as the type II sodium-dependent phosphate co-transporter (NPT2A), uniquely bind only one PDZ domain (Mamonova et al. 2015). 

NHERF1 (TC# 8.A.24.1.1 and NHERF2 (E3KARP) (TC# 8.A.24.1.2) are homologous adapter proteins that play roles in membrane protein targeting, trafficking, and sorting (Park et al. 2005). Both NHERF1 and 2 interact with the Na+/H+ exchanger, NHE3, through their C-terminally extended second PDZ domain. The last 30 amino acids of these PDZ domain proteins interact with ezrin (TC# 8.A.25.1.1). Both soluble NHERF proteins have been purified (Park et al. 2005).

The carboxyl terminus of NHERF interacts with the FERM domain (a domain shared by protein 4.1, ezrin, radixin, and moesin) of a family of actin-binding proteins called the ezrin-radixin-moesin family (TC #8.A.25). NHERF enhances the channel activities of cystic fibrosis transmembrane conductance regulator (CFTR) (TC #3.A.1.202.1). Binding of the FERM domain of ezrin to NHERF regulates the cooperative binding of NHERF to bring two cytoplasmic tails of CFTR into spatial proximity to each other. Ezrin binding activates the second PDZ domain of NHERF to interact with the cytoplasmic tails of CFTR (C-CFTR), so as to form a specific 2:1:1 (C-CFTR)2·NHERF·ezrin ternary complex. EPP50 is required both for plasma membrane localization and for maximal activation of CFTR (Broere et al., 2007). Without ezrin binding, the cytoplasmic tail of CFTR only interacts strongly with the first amino-terminal PDZ domain to form a 1:1 C-CFTR·NHERF complex. Because of the concentrated distribution of ezrin and NHERF in the apical membrane regions of epithelial cells and the diverse binding partners for the NHERF PDZ domains, the regulation of NHERF by ezrin may be employed as a general mechanism to assemble channels and receptors in the membrane cytoskeleton (Li et al., 2005).

The sodium-dependent glutamate transporter, glutamate transporter subtype 1 (GLT-1) is one of the main glutamate transporters in the brain. GLT-1 contains a COOH-terminal sequence similar to one in an isoform of Slo1 K+ channel protein previously shown to bind MAGI-1 (membrane-associated guanylate kinase with inverted orientation protein-1), a member of the EBP50 family (TC#8.A.24) (Zou et al., 2011). MAGI-1 is a scaffold protein which allows the formation of complexes between certain transmembrane proteins, actin-binding proteins, and other regulatory proteins. MAGI-1 is a binding partner of GLT-1. The interaction between MAGI-1 and GLT-1 was confirmed by co-immunoprecipitation. Immunofluorescence of MAGI-1 and GLT-1 demonstrated that the distribution of MAGI-1 and GLT-1 overlapped in astrocytes. Co-expression of MAGI-1 with GLT-1 in C6 Glioma cells resulted in a significant reduction in the surface expression of GLT-1, as assessed by cell-surface biotinylation. On the other hand, partial knockdown of endogenous MAGI-1 expression by small interfering RNA in differentiated cultured astrocytes increased glutamate uptake and the surface expression of endogenous GLT-1. Knockdown of MAGI-1 increased dihydrokainate-sensitive, Na+-dependent glutamate uptake, indicating that MAGI-1 regulates GLT-1-mediated glutamate uptake. These data suggest that MAGI-1 regulates surface expression of GLT-1 and the level of glutamate in the hippocampus (Zou et al., 2011). 

Many protein of TC families 8.A.22 and 8.A.24 and others contain PDZ, SH3 and kinase domains involved in signal transduction, often interacting with receptors and transporters. Therefore, these two families share about 400 aas in common.  PDZ proteins of the NHERF family act to stabilize and organize membrane targeting of multiple transmembrane proteins, including many clinically relevant drug transporters. These PDZ proteins are normally abundant at apical membranes, where they tether membrane-delimited transporters. NHERF expression is high at the apical membrane in polarized tissue such as intestinal, hepatic, and renal epithelia. NHERF proteins are determinants of drug transporter function in addition to their role in controlling membrane abundance and localization. They may have clinically significant roles in pharmacokinetics and pharmacodynamics of several pharmacologically active compounds and may affect drug action in cancer and chronic kidney disease. For these reasons, NHERF proteins represent a novel class of post-translational mediators of drug transport and novel targets for new drug development (Walsh et al. 2015).

References associated with 8.A.24 family:

Addi, C., A. Presle, S. Frémont, F. Cuvelier, M. Rocancourt, F. Milin, S. Schmutz, J. Chamot-Rooke, T. Douché, M. Duchateau, Q. Giai Gianetto, A. Salles, H. Ménager, M. Matondo, P. Zimmermann, N. Gupta-Rossi, and A. Echard. (2020). The Flemmingsome reveals an ESCRT-to-membrane coupling via ALIX/syntenin/syndecan-4 required for completion of cytokinesis. Nat Commun 11: 1941. 32321914
Bannert, K., P. Berlin, J. Reiner, H. Lemcke, R. David, R. Engelmann, and G. Lamprecht. (2020). SNX27 regulates DRA activity and mediates its direct recycling by PDZ-interaction in early endosomes at the apical pole of Caco2 cells. Am. J. Physiol. Gastrointest Liver Physiol 318: G854-G869. 32116023
Bhattacharya, S., C.B. Stanley, W.T. Heller, P.A. Friedman, and Z. Bu. (2019). Dynamic structure of the full-length scaffolding protein NHERF1 influences signaling complex assembly. J. Biol. Chem. [Epub: Ahead of Print] 31171716
Borisovska, M. (2018). Syntaxins on granules promote docking of granules via interactions with munc18. Sci Rep 8: 193. 29317735
Broere, N., J. Hillesheim, B. Tuo, H. Jorna, A.B. Houtsmuller, S. Shenolikar, E.J. Weinman, M. Donowitz, U. Seidler, H.R. de Jonge, and B.M. Hogema. (2007). Cystic Fibrosis Transmembrane Conductance Regulator Activation Is Reduced in the Small Intestine of Na+/H+ Exchanger 3 Regulatory Factor 1 (NHERF-1)- but Not NHERF-2-deficient Mice. J. Biol. Chem. 282: 37575-37584. 17947234
Brückner, K., J. Pablo Labrador, P. Scheiffele, A. Herb, P.H. Seeburg, and R. Klein. (1999). EphrinB ligands recruit GRIP family PDZ adaptor proteins into raft membrane microdomains. Neuron. 22: 511-524. 10197531
Cheng, J., B.D. Moyer, M. Milewski, J. Loffing, M. Ikeda, J.E. Mickle, G.R. Cutting, M. Li, B.A. Stanton, and W.B. Guggino. (2002). A Golgi-associated PDZ domain protein modulates cystic fibrosis transmembrane regulator plasma membrane expression. J. Biol. Chem. 277: 3520-3529. 11707463
Cheng, J., H. Wang, and W.B. Guggino. (2004). Modulation of mature cystic fibrosis transmembrane regulator protein by the PDZ domain protein CAL. J. Biol. Chem. 279: 1892-1898. 14570915
El-Haou, S., E. Balse, N. Neyroud, G. Dilanian, B. Gavillet, H. Abriel, A. Coulombe, A. Jeromin, and S.N. Hatem. (2009). Kv4 potassium channels form a tripartite complex with the anchoring protein SAP97 and CaMKII in cardiac myocytes. Circ Res 104: 758-769. 19213956
Engel, M., P. Snikeris, N. Matosin, K.A. Newell, X.F. Huang, and E. Frank. (2016). mGluR2/3 agonist LY379268 rescues NMDA and GABAA receptor level deficits induced in a two-hit mouse model of schizophrenia. Psychopharmacology (Berl) 233: 1349-1359. 26861891
Fanning, A.S., B.J. Jameson, L.A. Jesaitis, and J.M. Anderson. (1998). The tight junction protein ZO-1 establishes a link between the transmembrane protein occludin and the actin cytoskeleton. J. Biol. Chem. 273: 29745-29753. 9792688
Furuse, M., M. Itoh, T. Hirase, A. Nagafuchi, S. Yonemura, S. Tsukita, and S. Tsukita. (1994). Direct association of occludin with ZO-1 and its possible involvement in the localization of occludin at tight junctions. J. Cell Biol. 127: 1617-1626. 7798316
Giepmans, B.N. (2006). Role of connexin43-interacting proteins at gap junctions. Adv Cardiol 42: 41-56. 16646583
He, J., M. Bellini, J. Xu, A.M. Castleberry, and R.A. Hall. (2004). Interaction with cystic fibrosis transmembrane conductance regulator-associated ligand (CAL) inhibits beta1-adrenergic receptor surface expression. J. Biol. Chem. 279: 50190-50196. 15358775
Jeyifous, O., E.I. Lin, X. Chen, S.E. Antinone, R. Mastro, R. Drisdel, T.S. Reese, and W.N. Green. (2016). Palmitoylation regulates glutamate receptor distributions in postsynaptic densities through control of PSD95 conformation and orientation. Proc. Natl. Acad. Sci. USA 113: E8482-E8491. 27956638
Jurkiewicz, D., K. Michalec, K. Skowronek, and K.A. Nałęcz. (2017). Tight junction protein ZO-1 controls organic cation/carnitine transporter OCTN2 (SLC22A5) in a protein kinase C-dependent way. Biochim. Biophys. Acta. 1864: 797-805. 28257821
Li, J., Z. Dai, D. Jana, D.J. Callaway, and Z. Bu. (2005). Ezrin controls the macromolecular complexes formed between an adapter protein Na+/H+ exchanger regulatory factor and the cystic fibrosis transmembrane conductance regulator. J Biol Chem. 280: 37634-37643. 16129695
Mamonova, T., Q. Zhang, J.A. Khajeh, Z. Bu, A. Bisello, and P.A. Friedman. (2015). Canonical and Noncanonical Sites Determine NPT2A Binding Selectivity to NHERF1 PDZ1. PLoS One 10: e0129554. 26070212
Mitsou, I., H.A.B. Multhaupt, and J.R. Couchman. (2017). Proteoglycans, ion channels and cell-matrix adhesion. Biochem. J. 474: 1965-1979. 28546458
Nicolodi, M. and F. Sicuteri. (1996). Fibromyalgia and migraine, two faces of the same mechanism. Serotonin as the common clue for pathogenesis and therapy. Adv Exp Med Biol 398: 373-379. 8906292
Niu, W., X. Rong, Q. Zhao, X. Liu, L. Xu, S. Li, and X. Li. (2023). [Wine-processed enhances efficacy of aumolertinib against EGFRmutant non-small cell lung cancer xenografts in nude mouse brain]. Nan Fang Yi Ke Da Xue Xue Bao 43: 375-382. 37087581
Park, K.S., M.S. Jeong, J.H. Kim, and S.B. Jang. (2005). Overexpression, purification, and characterization of PDZ domain proteins NHERF and E3KARP in Escherichia coli. Protein Expr Purif 40: 197-202. 15721789
Philley, J.V., A. Kannan, and S. Dasgupta. (2016). MDA-9/Syntenin Control. J Cell Physiol 231: 545-550. 26291527
Ravi, A.S., M. Zeng, X. Chen, G. Sandoval, J. Diaz-Alonso, M. Zhang, and R.A. Nicoll. (2022). Long-term potentiation reconstituted with an artificial TARP/PSD-95 complex. Cell Rep 41: 111483. 36223737
Rogelj, B., J.C. Mitchell, C.C. Miller, and D.M. McLoughlin. (2006). The X11/Mint family of adaptor proteins. Brain Res Rev 52: 305-315. 16764936
Ruan, Y.C., Y. Wang, N. Da Silva, B. Kim, R.Y. Diao, E. Hill, D. Brown, H.C. Chan, and S. Breton. (2014). CFTR interacts with ZO-1 to regulate tight junction assembly and epithelial differentiation through the ZONAB pathway. J Cell Sci 127: 4396-4408. 25107366
Setoguchi, K., H. Otera, and K. Mihara. (2006). Cytosolic factor- and TOM-independent import of C-tail-anchored mitochondrial outer membrane proteins. EMBO. J. 25: 5635-5647. 17110923
Sun, N., Y.J. Qin, C. Xu, T. Xia, Z.W. Du, L.P. Zheng, A.A. Li, F. Meng, Y. Zhang, J. Zhang, X. Liu, T.Y. Li, D.Y. Zhu, and Q.G. Zhou. (2022). Design of fast-onset antidepressant by dissociating SERT from nNOS in the DRN. Science 378: 390-398. 36302033
Tan, H.L., S.L. Chiu, Q. Zhu, and R.L. Huganir. (2020). GRIP1 regulates synaptic plasticity and learning and memory. Proc. Natl. Acad. Sci. USA 117: 25085-25091. 32948689
Walsh, D.R., T.D. Nolin, and P.A. Friedman. (2015). Drug Transporters and Na+/H+ Exchange Regulatory Factor PSD-95/Drosophila Discs Large/ZO-1 Proteins. Pharmacol Rev 67: 656-680. 26092975
Wang, P., Z. Ye, and D.K. Banfield. (2020). A novel mechanism for the retention of Golgi membrane proteins mediated by the Bre5p/Ubp3p deubiquitinase complex. Mol. Biol. Cell 31: 2139-2155. 32673164
Xavier, R., S. Rabizadeh, K. Ishiguro, N. Andre, J.B. Ortiz, H. Wachtel, D.G. Morris, M. Lopez-Ilasaca, A.C. Shaw, W. Swat, and B. Seed. (2004). Discs large (Dlg1) complexes in lymphocyte activation. J. Cell Biol. 166: 173-178. 15263016
Yang, J., R. Sarker, V. Singh, P. Sarker, J. Yin, T.E. Chen, R. Chaerkady, X. Li, C.M. Tse, and M. Donowitz. (2015). The NHERF2 sequence adjacent and upstream of the ERM-binding domain affects NHERF2-ezrin binding and dexamethasone stimulated NHE3 activity. Biochem. J. 470: 77-90. 26251448
Yang, J., V. Singh, B. Cha, T.E. Chen, R. Sarker, R. Murtazina, S. Jin, N.C. Zachos, G.H. Patterson, C.M. Tse, O. Kovbasnjuk, X. Li, and M. Donowitz. (2013). NHERF2 protein mobility rate is determined by a unique C-terminal domain that is also necessary for its regulation of NHE3 protein in OK cells. J. Biol. Chem. 288: 16960-16974. 23612977
Yun, J.H., S.W. Park, K.J. Kim, J.S. Bae, E.H. Lee, S.H. Paek, S.U. Kim, S. Ye, J.H. Kim, and C.H. Cho. (2017). Endothelial STAT3 Activation Increases Vascular Leakage Through Downregulating Tight Junction Proteins: Implications for Diabetic Retinopathy. J Cell Physiol 232: 1123-1134. 27580405
Zeng, M., J. Díaz-Alonso, F. Ye, X. Chen, J. Xu, Z. Ji, R.A. Nicoll, and M. Zhang. (2019). Phase Separation-Mediated TARP/MAGUK Complex Condensation and AMPA Receptor Synaptic Transmission. Neuron. 104: 529-543.e6. 31492534
Zhang, W., Z. Zhang, Y. Zhang, and A.P. Naren. (2017). CFTR-NHERF2-LPA₂ Complex in the Airway and Gut Epithelia. Int J Mol Sci 18:. 28869532
Zou, S., J.D. Pita-Almenar, and A. Eskin. (2011). Regulation of glutamate transporter GLT-1 by MAGI-1. J Neurochem 117: 833-840. 21426345