New mutations and phenotypes associated with glutamate and aspartate transport in Chinese hamster ovary (CHO-K1) cells

Somat Cell Mol Genet. 1996 Mar;22(2):87-103. doi: 10.1007/BF02369900.


Two new Chinese hamster ovary cell (CHO-K1) mutants lacking amino acid transport System X-AG activity were isolated by [3H]aspartate suicide selection. These null mutants, Dd-B6 and Dd-B7, were analyzed by somatic cell hybridization, along with previously described partial-function mutants, Ed-A1 and Ed-B8. With respect to System X-AG activity, all four mutations fell into a single complementation group. By quantitative assay, the mutations in Ed-A1 and Ed-B8 behaved as simple recessives in fusions with wild type cells, while those in Dd-B6 and Dd-B7 were codominant. We have discovered that Ed-A1 and Ed-B8 are highly permeable to small neutral molecules. This high permeability phenotype was dominant to wild-type. Northern, Southern, and Western analyses indicated that System X-AG in CHO is not closely related to any of the three well characterized glutamate transporters represented by GLT-1, EAACI or GLAST.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Amino Acid Transport System X-AG
  • Animals
  • Aspartic Acid / metabolism*
  • Biological Transport
  • Brain Chemistry
  • CHO Cells
  • Carrier Proteins / analysis
  • Carrier Proteins / genetics
  • Carrier Proteins / physiology*
  • Cell Membrane / chemistry
  • Cell Membrane Permeability
  • Cricetinae
  • Excitatory Amino Acid Transporter 1
  • Genetic Complementation Test
  • Glutamate Plasma Membrane Transport Proteins
  • Glutamic Acid / metabolism*
  • Glycerol / metabolism
  • Glycoproteins / genetics
  • Hybrid Cells
  • Kinetics
  • Mice
  • Mutation*
  • Phenotype
  • RNA, Messenger / analysis
  • Symporters*
  • Urea / metabolism
  • Water / metabolism


  • Amino Acid Transport System X-AG
  • Carrier Proteins
  • Excitatory Amino Acid Transporter 1
  • Glutamate Plasma Membrane Transport Proteins
  • Glycoproteins
  • RNA, Messenger
  • Slc1a3 protein, mouse
  • Symporters
  • Water
  • Aspartic Acid
  • Glutamic Acid
  • Urea
  • Glycerol