@article{oai:tsukuba.repo.nii.ac.jp:00015327,
 author = {森尾, 貴広 and 桑山, 秀一 and Yoshino, Ryuji and Morio, Takahiro and Yamada, Yoko and Kuwayama, Hidekazu and Sameshima, Masazumi and Tanaka, Yoshimasa and Sesaki, Hiromi and Iijima, Miho},
 issue = {12},
 journal = {Eukaryotic cell},
 month = {Dec},
 note = {application/pdf, application/pdf, Ammonia has been shown to function as a morphogen at multiple steps during development of
the cellular slime mold Dictyostelium discoideum; however, it is largely unknown how
intracellular ammonia levels are controlled. In the Dictyostelium genome, there are five genes
that encode putative ammonium transporters, amtA, amtB, amtC, rhgA, and rhgB. Here, we
show that AmtA regulates ammonia homeostasis during growth and development. We found
that cells lacking amtA had increased levels of ammonia/ammonium, whereas their extracellular
ammonia/ammonium levels were highly decreased. These results suggest that AmtA mediates
excretion of ammonium. Supporting a role for AmtA in ammonia homeostasis, AmtA mRNA is
expressed throughout the life cycle, and its expression level increases during development.
Importantly, AmtA-mediated ammonia homeostasis is critical for many developmental processes.
amtA- cells are more sensitive to NH4Cl in chemotaxis towards cAMP and in formation of
multicellular aggregates. Furthermore, even in the absence of exogenously added ammonia, we
found that amtA- cells produced many small fruiting bodies and viability and germination of
amtA- spores were dramatically compromised. Taken together, our data clearly demonstrate
that AmtA regulates ammonia homeostasis and plays important roles in multiple developmental
processes in Dictyostelium.},
 pages = {2419--2428},
 title = {Regulation of Ammonia Homeostasis by the Ammonium Transporter AmtA in Dictyostelium discoideum},
 volume = {6},
 year = {2007}
}