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XB-ART-46265
Cell Physiol Biochem 2012 Jan 01;306:1444-55. doi: 10.1159/000343332.
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PSD-95 interacts with NBCn1 and enhances channel-like activity without affecting Na/HCO(3) cotransport.

Lee S , Yang HS , Kim E , Ju EJ , Kwon MH , Dudley RK , Smith Y , Yun CC , Choi I .


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BACKGROUND/AIMS: The sodium/bicarbonate transporter NBCn1 plays an essential role in intracellular pH regulation and transepithelial HCO(3)(-) movement in the body. NBCn1 also has sodium channel-like activity uncoupled to Na/HCO(3) cotransport. We previously reported that NBCn1 interacts with the postsynaptic density protein PSD-95 in the brain. Here, we elucidated the structural determinant and functional consequence of NBCn1/PSD-95 interaction. METHODS: RESULTS: In rat hippocampal CA3 neurons, NBCn1 was localized to the postsynaptic membranes of both dendritic shafts and spines and occasionally to the presynaptic membranes. A GST/NBCn1 fusion protein containing the C-terminal 131 amino acids of NBCn1 pulled down PSD-95 from rat brain lysates, whereas GST/NBCn1-ΔETSL (deletion of the last four amino acids) and GST/NBCn2 (NCBE) lacking the same ETSL did not. NBCn1 and PSD-95 were coimmunoprecipitated in HEK 293 cells, and their interaction did not affect the efficacy of PSD-95 to bind to the NMDA receptor NR2A. PSD-95 has negligible effects on intracellular pH changes mediated by NBCn1 in HEK 293 cells and Xenopus oocytes. However, PSD-95 increased an ionic conductance produced by NBCn1 channel-like activity. This increase was abolished by NBCn1-ΔETSL or by the peptide containing the last 15 amino acids of NBCn1. CONCLUSION: Our data suggest that PSD-95 interacts with NBCn1 and increases its channel-like activity while negligibly affecting Na/HCO(3) cotransport. The possibility that the channel-like activity occurs via an intermolecular cavity of multimeric NBCn1 proteins is discussed.

???displayArticle.pubmedLink??? 23183381
???displayArticle.pmcLink??? PMC3705566
???displayArticle.link??? Cell Physiol Biochem
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Species referenced: Xenopus
Genes referenced: dlg4 grin2a psd slc4a7

References [+] :
Alper, Molecular physiology of SLC4 anion exchangers. 2006, Pubmed, Xenbase