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 residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

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

gene In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...

. The RHD gene codes for the RhD

erythrocyte Red blood cells (RBCs), referred to as erythrocytes (, with -''cyte'' translated as 'cell' in modern usage) in academia and medical publishing, also known as red cells, erythroid cells, and rarely haematids, are the most common type of blood ce ...

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, moiety, foreign particulate matter, or an allergen, such as pollen, 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. RHD has sequence similarity to RHCE, RhAG, RhBG, 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; indicat ...

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 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 commonl ...

Antibodies An antibody (Ab) or immunoglobulin (Ig) is a large, Y-shaped protein belonging to the immunoglobulin superfamily which is used by the immune system to identify and neutralize antigens such as bacteria and viruses, including those that caus ...

to the RhD protein can cause

Rh disease Rh disease (also known as rhesus isoimmunization, Rh (D) disease, or rhesus incompatibility, and blue baby disease) is a type of hemolytic disease of the fetus and newborn (HDFN). The term "Rh disease" is commonly used to refer to HDFN due to a ...

References

Further reading

See also