Rh proteins: Key structural and functional components of the red cell membrane

Kim, Caroline Le Van; Colin, Yves; Cartron, Jean‐Pierre

doi:10.1016/j.blre.2005.04.002

Cited by 116 publications

(110 citation statements)

References 144 publications

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“…Interestingly, most of these proteins coexist in a mega-complex that links the membrane to the underlying cytoskeleton. 67 Importantly, mouse Rh-cde, GPA, CD59, CD47, and Ermap/Scianna genes all contain CACC sites in their proximal promoters that are likely to bind EKLF. 7,28,68 Together, our results strongly suggest that EKLF coordinates expression of many key blood group antigens and associated proteins that link the membrane to the cytoskeleton ( Figure 5).…”

Section: Blood Group Antigens and Eklfmentioning

confidence: 99%

A global role for EKLF in definitive and primitive erythropoiesis

Hodge

Coghill

Keys

et al. 2006

Blood

197

288

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Section: Blood Group Antigens and Eklfmentioning

confidence: 99%

A global role for EKLF in definitive and primitive erythropoiesis

Hodge

Coghill

Keys

et al. 2006

Blood

197

288

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“…Chain et al, 2003;Huang and Peng, 2005;Weihrauch, 2006). Structural and functional studies have revealed that Rh proteins are transporters of ammonia, a property shared with AmtB, their Escherichia coli homologue (for reviews, see Planelles, 2007;Van Kim et al, 2006;Weiner and Hamm, 2007). There is some conflict as to whether the primary substrate is NH 3 or NH 4 + , but most evidence points to NH 3 (Javelle et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

The effects of CO2 and external buffering on ammonia excretion and Rhesus glycoprotein mRNA expression in rainbow trout

Nawata

Wood

2008

Journal of Experimental Biology

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SUMMARYRhesus (Rh) proteins were recently characterized as ammonia gas (NH 3 ) channels. Studies indicate, however, that Rh proteins also facilitate CO 2 transport in a green alga and in human erythrocytes. Previously, we reported that Rh mRNA expression in various rainbow trout tissues responded to high environmental ammonia. To determine whether or not Rh proteins may also be involved in CO 2 transport in rainbow trout, we examined the effects of a 12 h exposure to external hypercapnia (1% CO 2 in air) on Rh mRNA expression in the gill, skin and erythrocytes. External hypercapnic conditions lowered the water pH and facilitated ammonia excretion; therefore, we also studied the effects of hypercapnia and normocapnia in the presence of 10 mmol l -1 Hepesbuffered water. Hepes treatment prevented water acidification, but resulted in elevated plasma ammonia levels and reduced ammonia excretion rates. Hypercapnia exposure without buffering did not elicit changes in Rh mRNA expression in the gill or skin. However, Rhcg2 mRNA expression was downregulated in the gills and upregulated in the skin of both normocapnia-and hypercapnia-exposed fish in Hepes-buffered water. mRNA expression of a newly cloned Rhbg2 cDNA was downregulated in the skin of fish exposed to buffered water, and Rhag mRNA expression in erythrocytes was decreased with exposure to normocapnia in buffered water but not with hypercapnia exposure in either buffered or unbuffered water. With the aid of Hepes buffering, we were able to observe the effects of both CO 2 and ammonia on Rh mRNA expression. Overall, we conclude that high CO 2 did not directly elicit changes in Rh mRNA transcription levels in the gill and skin, and that the changes observed probably reflect responses to high plasma ammonia, mirroring those in trout exposed to high environmental ammonia. Therefore a dual function for gill and skin Rh proteins in CO 2 and ammonia transport is not evident from these results. Rhag expression, however, responded differentially to high CO 2 and high ammonia, suggesting a possible dual role in the erythrocytes.

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“…Although over 300 members of the AMT/MEP/Rh family have currently been assigned based on amino acid sequence similarity (Pfam accession number PF00909), an ammonium transport function has not been confirmed for the vast majority of these sequences. Functional permeases have been described for bacteria, fungi, plants (reviewed in reference 54), and humans, where the rhesus blood group polypeptides, which display significant sequence identity to AMT/MEP proteins, have been shown to function as ammonium transporters in other systems (27,53,55,59). The structure of Escherichia coli AmtB has been determined up to 1.35-Å resolution, and structural analysis revealed that the protein functions as a trimer that recruits ammonium which is then channeled as ammonia (18,58).…”

mentioning

confidence: 99%

Differential Expression of Aspergillus nidulans Ammonium Permease Genes Is Regulated by GATA Transcription Factor AreA

et al. 2006

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The movement of ammonium across biological membranes is mediated in both prokaryotes and eukaryotes by ammonium transport proteins (AMT/MEP) that constitute a family of related sequences. We have previously identified two ammonium permeases in Aspergillus nidulans, encoded by the meaA and mepA genes. Here we show that meaA is expressed in the presence of ammonium, consistent with the function of MeaA as the main ammonium transporter required for optimal growth on ammonium as a nitrogen source. In contrast, mepA, which encodes a high-affinity ammonium permease, is expressed only under nitrogen-limiting or starvation conditions. We have identified two additional AMT/MEP-like genes in A. nidulans, namely, mepB, which encodes a second high-affinity ammonium transporter expressed only in response to complete nitrogen starvation, and mepC, which is expressed at low levels under all nitrogen conditions. The MepC gene product is more divergent than the other A. nidulans AMT/MEP proteins and is not thought to significantly contribute to ammonium uptake under normal conditions. Remarkably, the expression of each AMT/MEP gene under all nitrogen conditions is regulated by the global nitrogen regulatory GATA factor AreA. Therefore, AreA is also active under nitrogen-sufficient conditions, along with its established role as a transcriptional activator in response to nitrogen limitation.Ammonium transport proteins (AMT/MEP) have been identified in bacteria, fungi, plants, and animals and constitute a conserved family of polytopic membrane proteins (54). AMT/MEP proteins are predicted to contain 11 transmembrane (TM) helices with an N out -C in topology (26, 48). Bioinformatic topology predictions indicate that bacterial AMT/MEP proteins generally contain an additional N-terminal TM domain but that this region acts as a signal peptide which is removed from the mature protein (9). Aside from the small cytoplasmic loop between TM domains 3 and 4 that displays sequence similarity to a major facilitator superfamily motif (34), the AMT/MEP sequences represent a unique group of transport membrane proteins. Although over 300 members of the AMT/MEP/Rh family have currently been assigned based on amino acid sequence similarity (Pfam accession number PF00909), an ammonium transport function has not been confirmed for the vast majority of these sequences. Functional permeases have been described for bacteria, fungi, plants (reviewed in reference 54), and humans, where the rhesus blood group polypeptides, which display significant sequence identity to AMT/MEP proteins, have been shown to function as ammonium transporters in other systems (27,53,55,59). The structure of Escherichia coli AmtB has been determined up to 1.35-Å resolution, and structural analysis revealed that the protein functions as a trimer that recruits ammonium which is then channeled as ammonia (18,58). Genetic, molecular, and/or physiological evidence suggests that AMT/MEP proteins can function as homoand/or heterocomplexes (6,25,29,34).The presence of multiple ammonium ...

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Rh proteins: Key structural and functional components of the red cell membrane

Cited by 116 publications

References 144 publications

A global role for EKLF in definitive and primitive erythropoiesis

A global role for EKLF in definitive and primitive erythropoiesis

The effects of CO2 and external buffering on ammonia excretion and Rhesus glycoprotein mRNA expression in rainbow trout

Differential Expression of Aspergillus nidulans Ammonium Permease Genes Is Regulated by GATA Transcription Factor AreA

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