Characterization of human RhCG and mouse Rhcg as novel nonerythroid Rh glycoprotein homologues predominantly expressed in kidney and testis
In mammals, the Rh family includes the variable Rh polypeptides and invariant RhAG glycoprotein. These polytopic proteins are confined to the erythroid lineage and are assembled into a multisubunit complex essential for Rh antigen expression and plasma membrane integrity. Here, we report the characterization of RhCG and Rhcg, a pair of novel Rh homologues present in human and mouse nonerythroid tissues. Despite sharing a notable similarity to the erythroid forms, including the 12-transmembrane topological fold, the RHCG/Rhcg pair is distinct in chromosome location, genomic organization, promoter structure, and tissue-specific expression. RHCG and Rhcg map at 15q25 of human chromosome 15 and the long arm of mouse chromosome 7, respectively, each having 11 exons and a CpG-rich promoter. Northern blots detected kidney and testis as the major organs of RHCG or Rhcg expression. In situ hybridization revealed strong expression of Rhcg in the kidney collecting tubules and testis seminiferous tubules. Confocal imaging of transiently expressed green fluorescence protein fusion proteins localized RhCG exclusively to the plasma membrane, a distribution confirmed by cellular fractionation and Western blot analysis. In vitro translation and ex vivo expression showed that RhCG carries a complex N-glycan, probably at the 48NLS50 sequon of exoloop 1. These results pinpoint RhCG and Rhcg as novel polytopic membrane glycoproteins that may function as epithelial transporters maintaining normal homeostatic conditions in kidney and testis.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Director. Office of Science. Office of Biological and Environmental Research; National Institutes of Health Grant HL54459 (US)
- DOE Contract Number:
- AC03-76SF00098
- OSTI ID:
- 828553
- Report Number(s):
- LBNL-47883; JBCHA3; R&D Project: LGFGAA; TRN: US200427%%463
- Journal Information:
- Journal of Biological Chemistry, Vol. 275, Issue 33; Other Information: Journal Publication Date: 08/18/2000; PBD: 23 May 2000; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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