Rh blood group, D antigen also known as Rh polypeptide 1 (RhPI) or cluster of differentiation 240D (CD240D) is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

that in humans is encoded by the ''RHD''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

. The RHD gene codes for the RhD

erythrocyte Red blood cells (RBCs), also referred to as red cells, red blood corpuscles (in humans or other animals not having nucleus in red blood cells), haematids, erythroid cells or erythrocytes (from Greek ''erythros'' for "red" and ''kytos'' for "holl ...

membrane protein Membrane proteins are common proteins that are part of, or interact with, biological membranes. Membrane proteins fall into several broad categories depending on their location. Integral membrane proteins are a permanent part of a cell membrane ...

that is the Rh factor

antigen In immunology, an antigen (Ag) is a molecule or molecular structure or any foreign particulate matter or a pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. ...

of the

Rh blood group system The Rh blood group system is a human blood group system. It contains proteins on the surface of red blood cells. After the ABO blood group system, it is the most likely to be involved in transfusion reactions. The Rh blood group system consists ...

. RHD has sequence similarity to RHCE,

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. ...

RhBG Rh family, B glycoprotein, also known as RHBG, is an ammonia transporter protein which in humans is encoded by the ''RHBG'' gene. Function RHBG and RHCG are non-erythroid members of the Rhesus blood group system, Rhesus (Rh) protein family that ...

, and

RhCG Rh family, C glycoprotein, also known as RHCG, is a protein that in humans is encoded by the ''RHCG'' gene. Function RHCG plays a critical role in ammonium handling and pH homeostasis in the kidney. The structure of the RHCG protein; indicates ...

and these five genes constitute the Rh family. It was proposed that the

Rh complex is a heterotrimer of RhAG, RhD, and RhCE protein subunits. RhAG is a functional

ammonia transporter Ammonia transportersTC# 1.A.11 are structurally related membrane transport proteins called Amt proteins (ammonia transporters) in bacteria and plants, methylammonium/ammonium permeases (MEPs) in yeast, or Rhesus (Rh) proteins in chordates. In huma ...

and is required for normal

cell surface The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates and protects the interior of all cells from the outside environment ( ...

expression of RhD and RhCE. Patients who lack RhD/RhCE/RhAG on the surface of their erythrocytes have

hemolytic anemia Hemolytic anemia or haemolytic anaemia is a form of anemia due to hemolysis, the abnormal breakdown of red blood cells (RBCs), either in the blood vessels (intravascular hemolysis) or elsewhere in the human body (extravascular). This most commonly ...

Antibodies An antibody (Ab), also known as an immunoglobulin (Ig), is a large, Y-shaped protein used by the immune system to identify and neutralize foreign objects such as pathogenic bacteria and viruses. The antibody recognizes a unique molecule of the ...

to the RhD protein can cause

Rh disease Rh disease (also known as rhesus isoimmunization, Rh (D) disease, and blue baby disease) is a type of hemolytic disease of the fetus and newborn (HDFN). HDFN due to anti-D antibodies is the proper and currently used name for this disease as the ...

Model organisms

Model organism A model organism (often shortened to model) is a non-human species that is extensively studied to understand particular biological phenomena, with the expectation that discoveries made in the model organism will provide insight into the workin ...

s have been used in the study of RHD function. A conditional

knockout mouse A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or "knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are importan ...

line, called ''Rhd^{tm1a(EUCOMM)Wtsi}'' was generated as part of the

International Knockout Mouse Consortium The International Knockout Mouse Consortium (IKMC) is a scientific endeavour to produce a collection of mouse embryonic stem cell lines that together lack every gene in the genome, and then to distribute the cells to scientific researchers to crea ...

program — a high-throughput mutagenesis project to generate and distribute animal models of disease to interested scientists. Male and female animals underwent a standardized

phenotypic screen In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology or physical form and structure, its developmental processes, its biochemical and physiological proper ...

to determine the effects of deletion. Twenty five tests were carried out on

mutant In biology, and especially in genetics, a mutant is an organism or a new genetic character arising or resulting from an instance of mutation, which is generally an alteration of the DNA sequence of the genome or chromosome of an organism. It ...

mice and one significant abnormality was observed:

homozygous Zygosity (the noun, zygote, is from the Greek "yoked," from "yoke") () is the degree to which both copies of a chromosome or gene have the same genetic sequence. In other words, it is the degree of similarity of the alleles in an organism. Mo ...

mutant males had a decrease in mean corpuscular

hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyte ...

Model organisms

References

Further reading

See also