scholarly journals Mechanism of NH 4 + Recruitment and NH 3 Transport in Rh Proteins

Structure ◽  
2015 ◽  
Vol 23 (8) ◽  
pp. 1550-1557 ◽  
Author(s):  
Sefer Baday ◽  
Esam A. Orabi ◽  
Shihao Wang ◽  
Guillaume Lamoureux ◽  
Simon Bernèche
Keyword(s):  
Rh Proteins

scholarly journals Structure and expression of the RH locus in the Rh-deficiency syndrome

Blood ◽  
1993 ◽  
Vol 82 (2) ◽  
pp. 656-662 ◽  
Author(s):  
B Cherif-Zahar ◽  
V Raynal ◽  
C Le Van Kim ◽  
AM D'Ambrosio ◽  
P Bailly ◽  
...  
Keyword(s):  
Transcriptional Activity ◽  
Deficiency Syndrome ◽  
Autosomal Locus ◽  
Chain Reaction ◽  
Rh Proteins ◽  
Polymerase Chain ◽  
Silent Allele ◽  
General Organization ◽  
Chronic Hemolytic Anemia ◽  
Inhibitor Gene

Red blood cell deficiency of Rh proteins is associated with morphologic and functional abnormalities of erythrocytes and with a chronic hemolytic anemia of varying severity. Rh-deficiency may be the result of homozygosity either for a silent allele at the RH locus (Rhnull amorph type) or for a recessive inhibitor gene(s) at an autosomal locus unlinked to RH locus (Rhnull regulator and Rhmod). In this report, we investigated the RH locus structure of Rh-deficient individuals by Southern analysis using cDNA and exon-specific probes deduced from the recent cloning of Rh genes (CcEe and D). As expected from family studies indicating that Rhmod and Rhnull regulator individuals are unable to express Rh antigens but are able to convey functional Rh genes from one generation to another, no alteration of the Rh genes was detected in these variants. Although Rhnull of the amorph type arose by inheritance of a pair of silent alleles at the RH locus, the general organization of the unique CcEe gene in the genome of the particular individual under examination was apparently normal and indistinguishable from a Rh-negative chromosome. More surprisingly, no mutation could be detected by sequencing the polymerase chain reaction (PCR)-amplified reticulocyte mRNAs, suggesting that the RH locus of this patient might be altered in its transcriptional activity. Through hybridization with exon-specific probes, we were also able to determine the zygosity for the D gene in DNA samples from individuals of known genotypes; using this approach, we found that Rhnull regulator variants could be either of the DD, Dd, or dd genotypes. These findings suggest that the postulated inhibitor gene(s) can negatively suppress the RH locus expression from chromosomes carrying either one or two of the Rh genes.

Fractional attachment of CD47 (IAP) to the erythrocyte cytoskeleton and visual colocalization with Rh protein complexes

Blood ◽  
2003 ◽  
Vol 101 (3) ◽  
pp. 1194-1199 ◽  
Author(s):  
Kris Noel Dahl ◽  
Connie M. Westhoff ◽  
Dennis E. Discher
Keyword(s):  
Protein Complexes ◽  
Surface Expression ◽  
Membrane Skeleton ◽  
Red Cells ◽  
Cell Periphery ◽  
Red Cell ◽  
Red Cell Membrane ◽  
Rh Proteins ◽  
Glycophorin C ◽  
Reduced Surface

Abstract Interactions of CD47 and RhAG and the Rh proteins are visualized between one another and with the cytoskeleton of intact erythrocytes. In a first study, CD47 is labeled with a phycoerythrin (PhE)– tagged antibody, which generates discrete spots that reflect induced clusters of CD47. Rh and RhAG colocalize with each other and to these induced clusters, whereas Band 3 and glycophorin C remain more homogeneously dispersed on the cell periphery. In a second study, red cells are aspirated into a micropipette, and immunofluorescent maps of the surface gradients that develop for CD47 and RhAG determine cytoskeletal connectivity. CD47 and RhAG gradients on normal red cells prove to be nearly identical and also appear intermediate to those found for the fluid bilayer and network-linked glycophorin C. Similar gradients are obtained for CD47 on Rhnull cells, suggesting that linkage of CD47 to the spectrin-actin skeleton is independent of Rh or RhAG and is not affected by CD47's reduced surface expression on these cells. The results show that CD47 colocalizes with Rh and RhAG but is fractionally attached to the red cell membrane skeleton independent of these and other major integral membrane proteins involved in cytoskeletal attachment. The results imply a homogeneous base distribution of CD47, restrained by cytoskeleton linkages, plus a smaller fraction of CD47, which is able to diffuse in the membrane.

Nitrogen excretion in developing zebrafish (Danio rerio): a role for Rh proteins and urea transporters

2009 ◽  
Vol 296 (5) ◽  
pp. F994-F1005 ◽  
Author(s):  
M. H. Braun ◽  
S. L. Steele ◽  
M. Ekker ◽  
S. F. Perry
Keyword(s):  
Danio Rerio ◽  
Ammonia Excretion ◽  
Nitrogen Excretion ◽  
Zebrafish Embryos ◽  
Relative Importance ◽  
Adult Fish ◽  
Total Ammonia ◽  
Developmental Feature ◽  
Rh Proteins ◽  
Delayed Maturation

Injection of antisense oligonucleotide morpholinos to elicit selective gene knockdown of ammonia (Rhag, Rhbg, and Rhcg1) or urea transporters (UT) was used as a tool to assess the relative importance of each transporter to nitrogen excretion in developing zebrafish ( Danio rerio). Knockdown of UT caused urea excretion to decrease by ∼90%, whereas each of the Rh protein knockdowns resulted in an ∼50% reduction in ammonia excretion. Contrary to what has been hypothesized previously for adult fish, each of the Rh proteins appeared to have a similar effect on total ammonia excretion, and thus all are required to facilitate normal ammonia excretion in the zebrafish larva. As demonstrated in other teleosts, zebrafish embryos utilized urea to a much greater extent than adults and were effectively ureotelic until hatching. At that point, ammonia excretion rapidly increased and appeared to be triggered by a large increase in the mRNA expression of Rhag, Rhbg, and Rhcg1. Unlike the situation in the adult pufferfish ( 35 ), the various transporters are not specifically localized to the gills of the developing zebrafish, but each protein has a unique expression pattern along the skin, gills, and yolk sac. This disparate pattern of expression would appear to preclude interaction between the Rh proteins in zebrafish embryos. However, this may be a developmental feature of the delayed maturation of the gills, because as the embryos matured, expression of the transporters in and around the gills increased.

scholarly journals Two-dimensional iodopeptide mapping demonstrates that erythrocyte Rh D, c, and E polypeptides are structurally homologous but nonidentical

Blood ◽  
1988 ◽  
Vol 72 (4) ◽  
pp. 1424-1427
Author(s):  
D Blanchard ◽  
C Bloy ◽  
P Hermand ◽  
JP Cartron ◽  
AM Saboori ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Molecular Species ◽  
Two Dimensional ◽  
Structural Homology ◽  
Composite Pattern ◽  
Rh Proteins ◽  
The Individual ◽  
High Degree

The 32,000 molecular weight (mol wt) erythrocyte Rh D, c, and E polypeptides were separately purified from cDE/cDE erythrocytes by monoclonal immunoprecipitations and compared by two-dimensional iodopeptide mapping. Digestions of the isolated Rh polypeptides with alpha-chymotrypsin revealed a high degree of structural homology between c and E (13/14 iodopeptides were identical) and less striking homology between D and c or E (8/19 identical). The iodopeptide maps of Rh proteins purified by a nonimmunologic protocol from cDE/cDE erythrocytes were virtually identical to the composite pattern (D + c + E) deduced from the individual maps of Rh D, c, and E iodopeptides. Digestions of the isolated Rh polypeptides with trypsin revealed an overall homology of approximately 50% between iodopeptides derived from D, c, and E. These data indicate that the erythrocyte Rh D, c, and E antigens are carried by homologous but distinct molecular species; c and E appear more closely related to each other than to D.

scholarly journals Expression of the 32-Kd polypeptide of the Rh antigen

Blood ◽  
1993 ◽  
Vol 82 (3) ◽  
pp. 1006-1009 ◽  
Author(s):  
K Suyama ◽  
S Roy ◽  
R Lunn ◽  
J Goldstein
Keyword(s):  
Bone Marrow ◽  
Sodium Dodecyl ◽  
Protein Band ◽  
Chain Reaction ◽  
Cdna Insert ◽  
Free System ◽  
Antibody Preparation ◽  
Reticulocyte Lysate ◽  
Rh Proteins ◽  
Polymerase Chain

To develop procedures for the expression of Rh antigen-containing proteins, we prepared a previously cloned Rh cDNA by isolation from a human bone marrow library using polymerase chain reaction (PCR). The cDNA that encodes either Rh(E) or (e) antigens was inserted into a vector (pGEM7ZRh) and transcription/translation performed in a reticulocyte lysate system. This produced a major (32 Kd) and minor (30 Kd) protein band in the region of sodium dodecyl sulfate (SDS) gels where Rh proteins are known to migrate. These same two proteins were immunoprecipitated by a rabbit anti-Rh antibody preparation that reacts with all Rh proteins, confirming that Rh protein was expressed in this cell-free system. Transient expression of Rh protein in COS-1 cells was also accomplished using a transfection vector (pBC12BIPLRh) containing inserted Rh cDNA. COS-1 cells transfected with this vector also produced a 32-Kd protein band that formed an immune complex with rabbit anti-Rh, while cells transfected with the same vector minus the Rh cDNA insert did not yield any detectable Rh immune-complexed protein. This system should prove useful for studying the transport of Rh proteins within the cell and the expression of Rh antigenicity at the cell surface.

scholarly journals Development of Aedes aegypti (Diptera: Culicidae) mosquito larvae in high ammonia sewage in septic tanks causes alterations in ammonia excretion, ammonia transporter expression, and osmoregulation

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Andrea C. Durant ◽  
Andrew Donini
Keyword(s):  
Aedes Aegypti ◽  
Ammonia Excretion ◽  
Virgin Islands ◽  
Malpighian Tubules ◽  
Comparative Approach ◽  
Vector Mosquito ◽  
High Ammonia ◽  
Rh Proteins ◽  
Anal Papillae ◽  
Excretory Organs

AbstractLarvae of the disease vector mosquito, Aedes aegypti (L.) readily develop in ammonia rich sewage in the British Virgin Islands. To understand how the larvae survive in ammonia levels that are lethal to most animals, an examination of ammonia excretory physiology in larvae collected from septic-water and freshwater was carried out. A. aegypti larvae were found to be remarkably plastic in dealing with high external ammonia through the modulation of NH4+ excretion at the anal papillae, measured using the scanning ion-selective electrode technique (SIET), and NH4+ secretion in the primary urine by the Malpighian tubules when developing in septicwater. Ammonia transporters, Amt and Rh proteins, are expressed in ionoregulatory and excretory organs, with increases in Rh protein, Na+-K+-ATPase, and V-type-H+-ATPase expression observed in the Malpighian tubules, hindgut, and anal papillae in septic-water larvae. A comparative approach using laboratory A. aegypti larvae reared in high ammonia septic-water revealed similar responses to collected A. aegypti with regard to altered ammonia secretion and hemolymph ion composition. Results suggest that the observed alterations in excretory physiology of larvae developing in septic-water is a consequence of the high ammonia levels and that A. aegypti larvae may rely on ammonia transporting proteins coupled to active transport to survive in septic-water.

Carbon dioxide transport across membranes

2021 ◽  
Vol 11 (2) ◽  
pp. 20200090
Author(s):  
Marie Michenkova ◽  
Sara Taki ◽  
Matthew C. Blosser ◽  
Hyea J. Hwang ◽  
Thomas Kowatz ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Metal Binding ◽  
Drug Targets ◽  
Membrane Lipid ◽  
Carbon Dioxide Transport ◽  
Preliminary Work ◽  
Initial Work ◽  
Rh Proteins ◽  
Central Pore ◽  
Differential Selectivity

Carbon dioxide (CO 2 ) movement across cellular membranes is passive and governed by Fick's law of diffusion. Until recently, we believed that gases cross biological membranes exclusively by dissolving in and then diffusing through membrane lipid. However, the observation that some membranes are CO 2 impermeable led to the discovery of a gas molecule moving through a channel; namely, CO 2 diffusion through aquaporin-1 (AQP1). Later work demonstrated CO 2 diffusion through rhesus (Rh) proteins and NH 3 diffusion through both AQPs and Rh proteins. The tetrameric AQPs exhibit differential selectivity for CO 2 versus NH 3 versus H 2 O, reflecting physico-chemical differences among the small molecules as well as among the hydrophilic monomeric pores and hydrophobic central pores of various AQPs. Preliminary work suggests that NH 3 moves through the monomeric pores of AQP1, whereas CO 2 moves through both monomeric and central pores. Initial work on AQP5 indicates that it is possible to create a metal-binding site on the central pore's extracellular face, thereby blocking CO 2 movement. The trimeric Rh proteins have monomers with hydrophilic pores surrounding a hydrophobic central pore. Preliminary work on the bacterial Rh homologue AmtB suggests that gas can diffuse through the central pore and three sets of interfacial clefts between monomers. Finally, initial work indicates that CO 2 diffuses through the electrogenic Na/HCO 3 cotransporter NBCe1. At least in some cells, CO 2 -permeable proteins could provide important pathways for transmembrane CO 2 movements. Such pathways could be amenable to cellular regulation and could become valuable drug targets.

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