Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The human Rhesus-associated RhAG protein and a kidney homologue promote ammonium transport in yeast


The Rhesus blood-group antigens are defined by a complex association of membrane polypeptides that includes the non-glycosylated Rh proteins (RhD and RhCE) and the RHag glycoprotein, which is strictly required for cell surface expression of these antigens1. RhAG and the Rh polypeptides are erythroid-specific transmembrane proteins belonging to the same family (36% identity)2,3. Despite their importance in transfusion medicine, the function of RhAG and Rh proteins remains unknown, except that their absence in Rhnull individuals leads to morphological and functional abnormalities of erythrocytes, known as the Rh-deficiency syndrome. We recently found significant sequence similarity between the Rh family proteins, especially RhAG, and Mep/Amt ammonium transporters4,5. We show here that RhAG and also RhGK, a new human homologue expressed in kidney cells only, function as ammonium transport proteins when expressed in yeast. Both specifically complement the growth defect of a yeast mutant deficient in ammonium uptake. Moreover, ammonium efflux assays and growth tests in the presence of toxic concentrations of the analogue methylammonium indicate that RhAG and RhGK also promote ammonium export. Our results provide the first experimental evidence for a direct role of RhAG and RhGK in ammonium transport. These findings are of high interest, because no specific ammonium transport system has been characterized so far in human.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Immunodetection of the RhAG and RhGK proteins expressed in yeast.
Figure 2: RhAG and RhGK proteins complement a yeast mutant deficient in ammonium transport.
Figure 3: RhAG and RhGK proteins do not complement yeast mutants deficient in amino acid or potassium transport.
Figure 4: RhAG and RhGK proteins confer resistance to methylammonium to yeast cells.
Figure 5: RhAG and RhGK promote excretion of ammonium.
Figure 6: Northern-blot analysis of RhGK mRNA.

Accession codes




  1. 1

    Chérif-Zahar, B. et al. Candidate gene acting as a suppressor of the RH locus in most cases of Rh-deficiency. Nature Genet. 12, 168–173 (1996).

    Article  Google Scholar 

  2. 2

    Cartron, J.P. Red cell membrane and its disorders. in Baillière's Clinical Haematology (eds Tanner, M.J.A. & Anstee, D.J.) 655– 689 (Harcourt, London, 1999).

    Google Scholar 

  3. 3

    Avent, N.D. & Reid, M.E. The Rh blood group system: a review. Blood 95, 375– 387 (2000).

    CAS  Google Scholar 

  4. 4

    Marini, A.M., Urrestarazu, A., Beauwens, R. & Andre, B. The Rh (rhesus) blood group polypeptides are related to NH4+ transporters . Trends Biochem. Sci. 22, 460– 461 (1997).

    CAS  Article  Google Scholar 

  5. 5

    Matassi, G., Chérif-Zahar, B., Raynal, V., Rouger, P. & Cartron, J.P. Organization of the human RH50A gene (RHAG) and evolution of base composition of the RH gene family. Genomics 47, 286–293 ( 1998).

    CAS  Article  Google Scholar 

  6. 6

    Marini, A.M., Vissers, S., Urrestarazu, A. & Andre, B. Cloning and expression of the MEP1 gene encoding an ammonium transporter in Saccharomyces cerevisiae. EMBO J. 13, 3456 –3463 (1994).

    CAS  Article  Google Scholar 

  7. 7

    Ninnemann, O., Jauniaux, J.C. & Frommer, W.B. Identification of a high affinity NH4+ transporter from plants. EMBO J. 13, 3464– 3471 (1994).

    CAS  Article  Google Scholar 

  8. 8

    Marini, A.M., Soussi-Boudekou, S., Vissers, S. & Andre, B. A family of ammonium transporters in Saccharomyces cerevisiae. Mol. Cell. Biol. 17, 4282–4293 (1997).

    CAS  Article  Google Scholar 

  9. 9

    Seack, J., Pancer, Z., Muller, I.M. & Muller, W.E. Molecular cloning and primary structure of a Rhesus (Rh)-like protein from the marine sponge Geodia cydonium. Immunogenetics 46 , 493–498 (1997).

    CAS  Article  Google Scholar 

  10. 10

    Kitano, T., Sumiyama, K., Shiroishi, T. & Saitou, N. Conserved evolution of the Rh50 gene compared to its homologous Rh blood group gene. Biochem. Biophys. Res. Commun. 249, 78–85 (1998).

    CAS  Article  Google Scholar 

  11. 11

    Matassi, G., Chérif-Zahar, B., Pesole, G., Raynal, V. & Cartron, J.P. The members of the RH gene family (RH50 and RH30) followed different evolutionary pathways. J. Mol. Evol. 48, 151–159 ( 1999).

    CAS  Article  Google Scholar 

  12. 12

    Altschul, S.F. et al. Gapped BLAST and PSI-BLAST: a new generation of protein database search programs. Nucleic Acids Res. 25, 3389–3402 (1997).

    CAS  Article  Google Scholar 

  13. 13

    Huizenga, J.R., Tangerman, A. & Gips, C.H. Determination of ammonia in biological fluids. Ann. Clin. Biochem. 31, 529– 543 (1994).

    CAS  Article  Google Scholar 

  14. 14

    Dejong, C.H., Deutz, N.E. & Soeters, P.B. Ammonia and glutamine metabolism during liver insufficiency: the role of kidney and brain in interorgan nitrogen exchange. Scand. J. Gastroenterol. Suppl. 218, 61– 77 (1996).

    CAS  Article  Google Scholar 

  15. 15

    Good, D.W. & Knepper, M.A. Ammonia transport in the mammalian kidney. Am. J. Physiol. 248, F459–471 (1985).

    CAS  Google Scholar 

  16. 16

    Knepper, M.A., Packer, R. & Good, D.W. Ammonium transport in the kidney. Physiol. Rev. 69, 179–249 ( 1989).

    CAS  Article  Google Scholar 

  17. 17

    Lorenz, M.C. & Heitman, J. The MEP2 ammonium permease regulates pseudohyphal differentiation in Saccharomyces cerevisiae. EMBO J. 17, 1236–1247 ( 1998).

    CAS  Article  Google Scholar 

  18. 18

    Palkova, Z. et al. Ammonia mediates communication between yeast colonies. Nature 390, 532–536 ( 1997).

    CAS  Article  Google Scholar 

  19. 19

    Mumberg, D., Muller, R. & Funk, M. Regulatable promoters of Saccharomyces cerevisiae: comparison of transcriptional activity and their use for heterologous expression. Nucleic Acids Res. 22, 5767–5768 (1994).

    CAS  Article  Google Scholar 

  20. 20

    Jacobs, P., Jauniaux, J.C. & Grenson, M. A cis-dominant regulatory mutation linked to the argB-argC gene cluster in Saccharomyces cerevisiae. J. Mol. Biol. 139, 691–704 (1980).

    CAS  Article  Google Scholar 

  21. 21

    Ito, H., Fukuda, Y., Murata, K. & Kimura, A. Transformation of intact yeast cells treated with alkali cations. J. Bacteriol. 153, 163–168 ( 1983).

    CAS  Google Scholar 

  22. 22

    Galan, J.M., Moreau, V., Andre, B., Volland, C. & Haguenauer-Tsapis, R. Ubiquitination mediated by the Npi1p/Rsp5p ubiquitin-protein ligase is required for endocytosis of the yeast uracil permease . J. Biol. Chem. 271, 10946– 10952 (1996).

    CAS  Article  Google Scholar 

  23. 23

    Schagger, H. & von Jagow, G. Tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis for the separation of proteins in the range from 1 to 100 kDa. Anal. Biochem. 166, 368–379 (1987).

    CAS  Article  Google Scholar 

  24. 24

    Iraqui, I. et al. Amino acid signaling in Saccharomyces cerevisiae: a permease-like sensor of external amino acids and F-Box protein Grr1p are required for transcriptional induction of the AGP1 gene, which encodes a broad-specificity amino acid permease . Mol. Cell. Biol. 19, 989– 1001 (1999).

    CAS  Article  Google Scholar 

  25. 25

    Ko, C.H. & Gaber, R.F. TRK1 and TRK2 encode structurally related K+ transporters in Saccharomyces cerevisiae. Mol. Cell. Biol. 11, 4266–4273 (1991).

    CAS  Article  Google Scholar 

  26. 26

    Nakamura, R.L., Anderson, J.A. & Gaber, R.F. Determination of key structural requirements of a K+ channel pore. J. Biol. Chem. 272, 1011–1018 (1997).

    CAS  Article  Google Scholar 

Download references


We thank C. Hattab for help in preparing rabbit antibodies; R. Gaber for yeast strains; and C. Jauniaux and S. Lecomte for technical contributions. This research was supported by The Commission of the European Communities and the Communauté Française de Belgique, Direction de la Recherche Scientifique. A.-M.M. is Chargé de recherches du Fonds National belge de la Recherche Scientifique. G.M. is currently a fellow of the International Centre for Genetic Engineering and Biotechnology.

Author information



Corresponding authors

Correspondence to Bruno André or Baya Chérif-Zahar.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Marini, AM., Matassi, G., Raynal, V. et al. The human Rhesus-associated RhAG protein and a kidney homologue promote ammonium transport in yeast. Nat Genet 26, 341–344 (2000).

Download citation

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing