title: Effects of Nt-truncation and coexpression of isolated Nt domains on the membrane trafficking of electroneutral Na+/HCO3- cotransporters.
abstract: The SLC4 genes are all capable of producing multiple variants by alternative splicing or using alternative promoters. The physiological consequences of such diversity are of great interest to investigators. Here, we identified two novel variants of the electroneutral Na(+)/HCO3- cotransporter NBCn1, one full-length starting with "MIPL" and the other Nt-truncated starting with "MDEL". Moreover, we identified a new promoter of Slc4a10 encoding NBCn2 and a novel type of Nt-truncated NBCn2 starting with "MHAN". When heterologously expressed, the new NBCn1 variants were well localized to the plasma membrane and exhibited characteristic NBCn1 activity. However, MHAN-NBCn2 was poorly localized on the plasma membrane. By deletion mutations, we identified the Nt regions important for the surface localization of NBCn2. Interestingly, coexpressing the full-length NBCn2 greatly enhances the surface abundance of the Nt-truncated NBCn2. Co-immunoprecipitation and bimolecular fluorescence complementation studies showed that the full-length and Nt-truncated NBCn2 interact with each other to form heterodimers in neuro-2A cells. Finally, we showed that the isolated Nt domain interacts with and enhances the surface abundance of the Nt-truncated NBCn2. The present study expands our knowledge of the NBCn1 and NBCn2 transcriptome, and provides insights into how the Nt domain could affect transporter function by regulating its membrane trafficking.
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Deng-Ke
authors.initials: DK
authors.lastname: Wang
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University at Buffalo: The State University of New York, Buffalo, NY 14214, USA.
authors.forename: Evan J
authors.initials: EJ
authors.lastname: Myers
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Guo
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Zhang-Dong
authors.initials: ZD
authors.lastname: Xie
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: De-Zhi
authors.initials: DZ
authors.lastname: Jiang
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Jia-Min
authors.initials: JM
authors.lastname: Li
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Peking University Health Science Center, Beijing 100091, China.
authors.forename: Jichun
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Genetics and Developmental Biology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Mugen
authors.initials: M
authors.lastname: Liu
authors.affiliation: Department of Physiology and Biophysics, School of Medicine, University at Buffalo: The State University of New York, Buffalo, NY 14214, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Parker
authors.affiliation: Department of Biophysics and Molecular Physiology, Key Laboratory of Molecular Biophysics of Ministry of Education, Huazhong University of Science and Technology School of Life Science and Technology, Wuhan, Hubei 430074, China.
authors.forename: Li-Ming
authors.initials: LM
authors.lastname: Chen
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019921:Biotinylation; D002462:Cell Membrane / Q000378:metabolism*; D005091:Exons / Q000235:genetics; D005453:Fluorescence; D017930:Genes, Reporter; D057809:HEK293 Cells; D006801:Humans; D007668:Kidney / Q000378:metabolism; D008156:Luciferases / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009865:Oocytes / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D017207:Rats, Sprague-Dawley; D027982:Sodium-Bicarbonate Symporters / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014981:Xenopus
chemical_list: D050505:Mutant Proteins; D012333:RNA, Messenger; C498904:Slc4a7 protein, mouse; D027982:Sodium-Bicarbonate Symporters; D008156:Luciferases