Biology:RHAG

Rh-associated glycoprotein (RHAG) is an ammonia transporter protein that in humans is encoded by the RHAG gene. RHAG has also recently been designated CD241 (cluster of differentiation 241). Mutations in the RHAG gene can cause stomatocytosis.

Function

The Rh blood group antigens (MIM 111700) are associated with human erythrocyte membrane proteins of approximately 30 kD, the so-called Rh30 polypeptides. Heterogeneously glycosylated membrane proteins of 50 and 45 kD, the Rh50 glycoproteins, are coprecipitated with the Rh30 polypeptides on immunoprecipitation with anti-Rh-specific mono- and polyclonal antibodies. The Rh antigens appear to exist as a multisubunit complex of CD47 (MIM 601028), LW (MIM 111250), glycophorin B (MIM 111740), and play a critical role in the Rh50 glycoprotein [supplied by OMIM].

Clinical diagnostic

Clinical testing in patient care for RhAG antigens follows published minimum quality and operational requirements, similar to red cell genotyping for any of the other recognized blood group systems. Molecular analysis can identify gene variants (alleles) that may affect RhAG antigens expression on the red cell membrane.

Interactions

RHAG has been shown to interact with ANK1.

See also

• Rh deficiency syndrome

References

This article incorporates text from the United States National Library of Medicine, which is in the public domain.

Further reading

• "The challenge of understanding ammonium homeostasis and the role of the Rh glycoproteins". Transfusion Clinique et Biologique 13 (1–2): 139–46. 2006. doi:10.1016/j.tracli.2006.02.008. PMID 16564724. 
• "Role of RhAG and AQP1 in NH3 and CO2 gas transport in red cell ghosts: a stopped-flow analysis". Transfusion Clinique et Biologique 13 (1–2): 117–22. 2006. doi:10.1016/j.tracli.2006.03.004. PMID 16574458. 
• "Isolation of cDNA clones for a 50 kDa glycoprotein of the human erythrocyte membrane associated with Rh (rhesus) blood-group antigen expression". The Biochemical Journal. 287 287 (1): 223–8. Oct 1992. doi:10.1042/bj2870223. PMID 1417776. 
• "Protein-sequence studies on Rh-related polypeptides suggest the presence of at least two groups of proteins which associate in the human red-cell membrane". The Biochemical Journal 256 (3): 1043–6. Dec 1988. doi:10.1042/bj2561043. PMID 3146980. 
• "Candidate gene acting as a suppressor of the RH locus in most cases of Rh-deficiency". Nature Genetics 12 (2): 168–73. Feb 1996. doi:10.1038/ng0296-168. PMID 8563755. 
• "The human Rh50 glycoprotein gene. Structural organization and associated splicing defect resulting in Rh(null) disease". The Journal of Biological Chemistry 273 (4): 2207–13. Jan 1998. doi:10.1074/jbc.273.4.2207. PMID 9442063. 
• "A novel single missense mutation identified along the RH50 gene in a composite heterozygous Rhnull blood donor of the regulator type". Blood 91 (4): 1458–63. Feb 1998. doi:10.1182/blood.V91.4.1458. PMID 9454778. 
• "Identification of 5' flanking sequence of RH50 gene and the core region for erythroid-specific expression". Biochemical and Biophysical Research Communications 243 (1): 233–40. Feb 1998. doi:10.1006/bbrc.1997.8023. PMID 9473510. Bibcode: 1998BBRC..243..233I. 
• "Rh50 glycoprotein gene and rhnull disease: a silent splice donor is trans to a Gly279→Glu missense mutation in the conserved transmembrane segment". Blood 92 (5): 1776–84. Sep 1998. doi:10.1182/blood.V92.5.1776. PMID 9716608. 
• "Rh-deficiency of the regulator type caused by splicing mutations in the human RH50 gene". Blood 92 (7): 2535–40. Oct 1998. doi:10.1182/blood.V92.7.2535. PMID 9746795. 
• "Rhmod syndrome: a family study of the translation-initiator mutation in the Rh50 glycoprotein gene". American Journal of Human Genetics 64 (1): 108–17. Jan 1999. doi:10.1086/302215. PMID 9915949. 
• "Molecular basis for Rh(null) syndrome: identification of three new missense mutations in the Rh50 glycoprotein gene". American Journal of Hematology 62 (1): 25–32. Sep 1999. doi:10.1002/(SICI)1096-8652(199909)62:1<25::AID-AJH5>3.0.CO;2-K. PMID 10467273. 
• "Cloning and characterization of erythroid-specific DNase I-hypersensitive site in human rhesus-associated glycoprotein gene". The Journal of Biological Chemistry 275 (35): 27324–31. Sep 2000. doi:10.1074/jbc.M003297200. PMID 10862620. 
• "The human Rhesus-associated RhAG protein and a kidney homologue promote ammonium transport in yeast". Nature Genetics 26 (3): 341–4. Nov 2000. doi:10.1038/81656. PMID 11062476. 
• "Identification of the erythrocyte Rh blood group glycoprotein as a mammalian ammonium transporter". The Journal of Biological Chemistry 277 (15): 12499–502. Apr 2002. doi:10.1074/jbc.C200060200. PMID 11861637. 
• "Cell-surface expression of RhD blood group polypeptide is posttranscriptionally regulated by the RhAG glycoprotein". Blood 100 (3): 1038–47. Aug 2002. doi:10.1182/blood.V100.3.1038. PMID 12130520. 
• "RhCG is downregulated in oesophageal squamous cell carcinomas, but expressed in multiple squamous epithelia". European Journal of Cancer 38 (14): 1927–36. Sep 2002. doi:10.1016/S0959-8049(02)00190-9. PMID 12204676. 
• "Fractional attachment of CD47 (IAP) to the erythrocyte cytoskeleton and visual colocalization with Rh protein complexes". Blood 101 (3): 1194–9. Feb 2003. doi:10.1182/blood-2002-04-1187. PMID 12393442. 

External links

• RHCE+protein,+human at the US National Library of Medicine Medical Subject Headings (MeSH)
• RhAG blood group system in the BGMUT blood group antigen gene mutation database