Cloning and functional characterization of a mammalian zinc transporter that confers resistance to zinc

EMBO J. 1995 Feb 15;14(4):639-49.

Abstract

A cDNA encoding a zinc transporter (ZnT-1) was isolated from a rat kidney cDNA expression library by complementation of a mutated, zinc-sensitive BHK cell line. This cDNA was used to isolate the homologous mouse ZnT-1 gene. The proteins predicted for these transporters contain six membrane-spanning domains, a large intracellular loop and a C-terminal tail. ZnT-1 is homologous to zinc and cobalt resistance genes of yeast. Immunocytochemistry with an antibody to a myc epitope added to the C-terminus of ZnT-1 revealed localization to the plasma membrane. Transformation of normal cells with a mutant ZnT-1 lacking the first membrane-spanning domain conferred zinc sensitivity on wild-type cells, suggesting that ZnT-1 functions as a multimer. Deletion of the first two membrane-spanning domains resulted in a non-functional molecule, whereas deletion of the C-terminal tail produced a toxic phenotype. Mutant cells have a slightly higher steady-state level of intracellular zinc and high basal expression of a zinc-dependent reporter gene compared with normal cells. Mutant cells have a lower turnover of 65Zn compared with normal cells or mutant cells transformed with ZnT-1. We propose that ZnT-1 transports zinc out of cells and that its absence accounts for the increased sensitivity of mutant cells to zinc toxicity.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Biological Transport
  • Cation Transport Proteins*
  • Cell Compartmentation
  • Cell Line
  • Cloning, Molecular
  • Cricetinae
  • Gene Expression
  • Genes
  • Kidney
  • Membrane Proteins / genetics*
  • Membrane Proteins / metabolism
  • Mice
  • Molecular Sequence Data
  • RNA, Messenger / genetics
  • Rats
  • Sequence Alignment
  • Sequence Homology, Nucleic Acid
  • Structure-Activity Relationship
  • Transfection
  • Zinc / metabolism*

Substances

  • Cation Transport Proteins
  • Membrane Proteins
  • RNA, Messenger
  • Slc30a1 protein, mouse
  • Slc30a1 protein, rat
  • Zinc

Associated data

  • GENBANK/U17132
  • GENBANK/U17133