Open AccessSystematic family‐wide analysis of sodium bicarbonate cotransporter NBC n1/ SLC 4A7 interactions with PDZ scaffold proteins
Author(s) -
Lee Hye Jeong,
Kwon Min Hyung,
Lee Soojung,
Hall Randy A.,
Yun C. Chris,
Choi Inyeong
Publication year - 2014
Publication title -
physiological reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.918
H-Index - 39
ISSN - 2051-817X
DOI - 10.14814/phy2.12016
Subject(s) - pdz domain , cotransporter , xenopus , biology , chemistry , cytosol , biochemistry , intracellular ph , plasma protein binding , scaffold protein , intracellular , microbiology and biotechnology , signal transduction , sodium , enzyme , gene , organic chemistry
NBCn1 (SLC4A7) plays a role in transepithelial HCO 3 − movement and intracellular pH maintenance in many tissues. In this study, we searched PDZ proteins capable of binding to NBCn1. We screened a protein array membrane, on which 96 different class I PDZ protein peptides were blotted, with the C‐terminal domain of NBCn1 fused to GST. Thirteen proteins were identified in these screens: MAGI‐3, NHERF‐1, NHERF‐2, PSD‐95, chapsyn‐110, ERBIN, MALS‐1, densin‐180, syntrophins α 1, β 2, γ 2, MUPP1, and PDZK1. After determining these binding partners, we analyzed the database of known and predicted protein interactions to obtain an NBCn1 interaction network. The network shows NBCn1 being physically and functionally associated with a variety of membrane and cytosolic proteins via the binding partners. We then focused on syntrophin γ 2 to examine the molecular and functional interaction between NBCn1 and one of the identified binding partners in the Xenopus oocyte expression system. GST/NBCn1 pulled down syntrophin γ 2 and conversely GST/syntrophin γ 2 pulled down NBCn1. Moreover, syntrophin γ 2 increased intracellular pH recovery, from acidification, mediated by NBCn1's Na/HCO 3 cotransport. Syntrophin γ 2 also increased an ionic conductance produced by NBCn1 channel‐like activity. Thus, syntrophin γ 2 regulates NBCn1 activity. In conclusion, this study demonstrates that NBCn1 binds to many PDZ proteins, which in turn may allow the transporter to associate with other physiologically important proteins.