title: Differential subcellular localization of the splice variants of the zinc transporter ZnT5 is dictated by the different C-terminal regions.
abstract: BACKGROUND
  Zinc is emerging as an important intracellular signaling molecule, as well as fulfilling essential structural and catalytic functions through incorporation in a myriad of zinc metalloproteins so it is important to elucidate the molecular mechanisms of zinc homeostasis, including the subcellular localizations of zinc transporters.
  
  
  RESULTS
  Two splice variants of the human SLC30A5 Zn transporter gene (ZnT5) have been reported in the literature. These variants differ at their N- and C-terminal regions, corresponding with the use of different 5' and 3' exons. We demonstrate that full length human ZnT5 variant B is a genuine transcript in human intestinal cells and confirm expression of both variant A and variant B in a range of untreated human tissues by splice variant-specific RT-PCR. Using N- or C-terminal GFP or FLAG fusions of both isoforms of ZnT5 we identify that the differential subcellular localization to the Golgi apparatus and ER respectively is a function of their alternative C-terminal sequences. These different C-terminal regions result from the incorporation into the mature transcript of either the whole of exon 14 (variant B) or only the 5' region of exon 14 plus exons 15-17 (variant A).
  
  
  CONCLUSIONS
  We thus propose that exons 15 to 17 include a signal that results in trafficking of ZnT5 to the Golgi apparatus and that the 3' end of exon 14 includes a signal that leads to retention in the ER.
authors: The Human Nutrition Research Centre, Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne, United Kingdom.
authors: Jared K
authors: JK
authors: Thornton
authors: Kathryn M
authors: KM
authors: Taylor
authors: Dianne
authors: D
authors: Ford
authors: Ruth A
authors: RA
authors: Valentine
mesh_terms: D017398:Alternative Splicing; D000595:Amino Acid Sequence; D027682:Cation Transport Proteins / Q000032:analysis* / Q000235:genetics* / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005091:Exons; D006056:Golgi Apparatus / Q000378:metabolism; D006801:Humans; D007422:Intestines / Q000166:cytology; D020033:Protein Isoforms; D021381:Protein Transport; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D027682:Cation Transport Proteins; D020033:Protein Isoforms; D012333:RNA, Messenger; C457225:SLC30A5 protein, human