The yeast Gdt1 protein mediates the exchange of H for Ca and Mn influencing the Golgi pH.

The GDT1 family is broadly spread and highly conserved among living organisms. GDT1 members have functions in key processes like glycosylation in humans and yeasts and photosynthesis in plants. These functions are mediated by their ability to transport ions.

K+-specific importers Trk1 and Trk2 play different roles in Ca2+ homeostasis and signalling in Saccharomyces cerevisiae cells.

The maintenance of K+ and Ca2+ homeostasis is crucial for many cellular functions. Potassium is accumulated in cells at high concentrations, while the cytosolic level of calcium, to ensure its signalling function, is kept at low levels and transiently increases in response to stresses. We examined Ca2+ homeostasis and Ca2+ signalling in Saccharomyces cerevisiae strains lacking plasma-membrane K+ influx (Trk1 and Trk2) or efflux (Tok1, Nha1 and Ena1-5) systems.

A new pH sensor localized in the Golgi apparatus of Saccharomyces cerevisiae reveals unexpected roles of Vph1p and Stv1p isoforms.

The gradual acidification of the secretory pathway is conserved and extremely important for eukaryotic cells, but until now there was no pH sensor available to monitor the pH of the early Golgi apparatus in Saccharomyces cerevisiae. Therefore, we developed a pHluorin-based sensor for in vivo measurements in the lumen of the Golgi. By using this new tool we show that the cis- and medial-Golgi pH is equal to 6.

Acidic and uncharged polar residues in the consensus motifs of the yeast Ca transporter Gdt1p are required for calcium transport.

The UPF0016 family is a recently identified group of poorly characterized membrane proteins whose function is conserved through evolution and that are defined by the presence of 1 or 2 copies of the E-φ-G-D-[KR]-[TS] consensus motif in their transmembrane domain. We showed that 2 members of this family, the human TMEM165 and the budding yeast Gdt1p, are functionally related and are likely to form a new group of Ca transporters. Mutations in TMEM165 have been demonstrated to cause a new type of rare human genetic diseases denominated as Congenital Disorders of Glycosylation.

Yeast Gdt1 is a Golgi-localized calcium transporter required for stress-induced calcium signaling and protein glycosylation.

Calcium signaling depends on a tightly regulated set of pumps, exchangers, and channels that are responsible for controlling calcium fluxes between the different subcellular compartments of the eukaryotic cell. We have recently reported that two members of the highly-conserved UPF0016 family, human TMEM165 and budding yeast Gdt1p, are functionally related and might form a new group of Golgi-localized cation/Ca(2+) exchangers. Defects in the human protein TMEM165 are known to cause a subtype of Congenital Disorders of Glycosylation.