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

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

 that in humans is encoded by the RHD gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

.

The RHD gene codes for the RhD erythrocyte membrane protein

Membrane protein

A membrane protein is a protein molecule that is attached to, or associated with the membrane of a cell or an organelle. More than half of all proteins interact with membranes.-Function:...

 that is the Rh factor antigen

Antigen

An antigen is a foreign molecule that, when introduced into the body, triggers the production of an antibody by the immune system. The immune system will then kill or neutralize the antigen that is recognized as a foreign and potentially harmful invader. These invaders can be molecules such as...

 of the Rh blood group system

Rh blood group system

The Rh blood group system is one of thirty current human blood group systems. Clinically, it is the most important blood group system after ABO. At Present, the Rh blood group system consists of 50 defined blood-group antigens, among which the 5 antigens D, C, c, E, and e are the most important...

. RHD has sequence similarity to RHCE

RHCE (gene)

Blood group Rh polypeptide is a protein that in humans is encoded by the RHCE gene. RHCE has also recently been designated CD240CE ....

, RhAG

RHAG

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

, RhBG

RHBG

Rh family, B glycoprotein, also known as RHBG, is an ammonia transporter protein which in humans is encoded by the RHBG gene.- Function :...

, and RhCG

RHCG

Rh family, C glycoprotein, also known as RHCG, is a protein which 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 that it has a hydrophobic ammonia-conducting channel thus...

 and these five genes constitute the Rh family

Rh blood group system

The Rh blood group system is one of thirty current human blood group systems. Clinically, it is the most important blood group system after ABO. At Present, the Rh blood group system consists of 50 defined blood-group antigens, among which the 5 antigens D, C, c, E, and e are the most important...

. It was proposed that the erythrocyte Rh complex is a heterotrimer of RhAG, RhD, and RhCE

RHCE (gene)

Blood group Rh polypeptide is a protein that in humans is encoded by the RHCE gene. RHCE has also recently been designated CD240CE ....

 protein subunits. RhAG is a functional ammonia transporter

Ammonia transporter

Ammonia transporters are structurally related membrane transport proteins called Amt proteins , methylammonium/ammonium permeases or RhAG, RhBG, and RhCG Rh family members in mammals. The RhAG, RhBG and RhCG proteins constitute solute carrier family 42...

 and is required for normal cell surface

Cell membrane

The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

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

Antibody

An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...

 to the RhD protein can cause Rh disease

Rh disease

Rh disease is one of the causes of hemolytic disease of the newborn...

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