Alternative titles; symbols
HGNC Approved Gene Symbol: GPR89B
Cytogenetic location: 1q21.2 Genomic coordinates (GRCh38): 1:147,928,420-148,025,934 (from NCBI)
By expression cloning using a mutagenized Chinese hamster ovary (CHO) FF8 cell line (C27 clone) and a human brain retroviral cDNA library, followed by screening for clones with restored transporter function and PCR analysis, Maeda et al. (2008) cloned human and hamster GPR89B, which they called GPHR. The deduced 455-amino acid human protein shares 96% and 92% amino acid identity with the respective mouse and Xenopus proteins. Immunoelectron microscopy and subcellular fractionation indicated that the majority of endogenous GPHR was localized to the Golgi. Western blot analysis and SDS-PAGE indicated that the GPHR channel was composed of trimeric GPHR, consistent with the presence of multiple substates of conductance.
Maeda et al. (2008) showed that expression of GPR89B restored the defective Golgi acidification, delayed protein transport, impaired glycosylation in the C27 EMS-mutagenized FF8 cell line clone. RNA interference (RNAi) showed that the reduction of GPR89B mRNA was sufficient to cause the defective Golgi acidification and associated phenotypes. They determined that the defective acidification and elevated luminal pH was specific to the Golgi and trans-Golgi network (TGN), and was not found in other organelles. In vitro reconstitution of GPR89B in an artificial lipid bilayer expressed in Sf9 insect cells and additional studies in semi-intact C27 cells showed that GPR89B displayed voltage-dependent anion channel activity that was selective for I-, Cl-, Br-, and F- ions, in that order of selectivity. Activity was inhibited by anion channel inhibitor DIDS (4,4-prime-diisothiocyanatostilbene-2,2-prime-disulfonic acid).
Hartz (2009) mapped the GPR89B gene to chromosome 1q21.1 based on an alignment of the GPR89B sequence (GenBank AF151035) with the genomic sequence (build 36.1). A nearly identical copy of GPR89B, GPR89A (612821), is located centromeric to GPR89B.
Hartz, P. A. Personal Communication. Baltimore, Md. 5/27/2009.
Maeda, Y., Ide, T., Koike, M., Uchiyama, Y., Kinoshita, T. GPHR is a novel anion channel critical for acidification and functions of the Golgi apparatus. Nature Cell Biol. 10: 1135-1145, 2008. [PubMed: 18794847] [Full Text: https://doi.org/10.1038/ncb1773]