GYPA | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Aliases | GYPA , CD235a, GPA, GPErik, GPSAT, HGpMiV, HGpMiXI, HGpSta(C), MN, MNS, PAS-2, glycophorin A (MNS blood group) | ||||||||||||||||||||||||||||||||||||||||||||||||||
External IDs | OMIM: 617922 HomoloGene: 48076 GeneCards: GYPA | ||||||||||||||||||||||||||||||||||||||||||||||||||
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Wikidata | |||||||||||||||||||||||||||||||||||||||||||||||||||
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Glycophorin A (MNS blood group), also known as GYPA, is a protein which in humans is encoded by the GYPA gene. [3] GYPA has also recently been designated CD235a (cluster of differentiation 235a).
Glycophorins A (GYPA; this protein) and B (GYPB) are major sialoglycoproteins of the human erythrocyte membrane which bear the antigenic determinants for the MN and Ss blood groups. In addition to the M or N and S or s antigens, that commonly occur in all populations, about 40 related variant phenotypes have been identified. These variants include all the variants of the Miltenberger complex and several isoforms of Sta; also, Dantu, Sat, He, Mg, and deletion variants Ena, S-s-U- and Mk. Most of the variants are the result of gene recombinations between GYPA and GYPB. [3]
GypA, GypB and GypE are members of the same family and are located on the long arm of chromosome 4 (chromosome 4q31). The family evolved via two separate gene duplication events. The initial duplication gave rise to two genes one of subsequently evolved into GypA and the other which give rise via a second duplication event to GypB and GypE. These events appear to have occurred within a relatively short time span. The second duplication appears to have occurred via an unequal crossing over event.
The GypA gene itself consists of 7 exons and has 97% sequence homology with GypB and GypE from the 5' untranslated transcription region (UTR) to the coding sequence encoding the first 45 amino acids. The exon at this point encodes the transmembrane domain. Within the intron downstream of this pint is an Alu repeat. The cross over event which created the genes ancestral to GypA and GypB/E occurred within this region.
GypA can be found in all primates. GypB can be found only in gorillas and some of the higher primates suggesting that the duplication events occurred only recently.
There are about one million copies of this protein per erythrocyte. [4]
The MNS blood group was the second set of antigens discovered. M and N were identified in 1927 by Landsteiner and Levine. S and s in were described later in 1947.
The frequencies of these antigens are
The M and N antigens differ at two amino acid residues: the M allele has serine at position 1 (C at nucleotide 2) and glycine at position 5 (G at nucleotide 14) while the N allele has leucine at position 1 (T at nucleotide 2) and glutamate at position 5 (A at nucleotide 14). Both glycophorin A and B bind the Vicia graminea anti-N lectin.
There are about 40 known variants in the MNS blood group system. These have arisen largely as a result of mutations within the 4 kb region coding for the extracellular domain. These include the antigens Mg, Dantu, Henshaw (He), Miltenberger, Nya, Osa, Orriss (Or), Raddon (FR) and Stones (Sta). Chimpanzees also have an MN blood antigen system. [5] In chimpanzees M reacts strong but N only weakly.
In individuals who lack both glycophorin A and B the phenotype has been designated Mk. [6]
The Dantu antigen was described in 1984. [7] The Dantu antigen has an apparent molecular weight of 29 kilodaltons (kDa) and 99 amino acids. The first 39 amino acids of the Dantu antigen are derived from glycophorin B and residues 40-99 are derived from glycophorin A. Dantu is associated with very weak s antigen, a protease-resistant N antigen and either very weak or no U antigen. There are at least three variants: MD, NE and Ph. [8] The Dantu phenotype occurs with a frequency of Dantu phenotype is ~0.005 in American Blacks and < 0.001 in Germans. [9]
The Henshaw (He) antigen is due to a mutation of the N terminal region. There are three differences in the first three amino acid residues: the usual form has Tryptophan 1-Serine-Threonine-Serine-Glycine 5 while Henshaw has Leucine 1-Serine-Threonine-Threonine-Glutamate 5. This antigen is rare in Caucasians but occurs at a frequency of 2.1% in US and UK of African origin. It occurs at the rate of 7.0% in blacks in Natal [10] and 2.7% in West Africans. [11] At least 3 variants of this antigen have been identified.
The Miltenberger (Mi) subsystem originally consisting of five phenotypes (Mia, Vw, Mur, Hil and Hut) [12] now has 11 recognised phenotypes numbered I to XI (The antigen 'Mur' is named after to the patient the original serum was isolated from - a Mrs Murrel.) The name originally given to this complex refers to the reaction erythrocytes gave to the standard Miltenberger antisera used to test them. The subclasses were based on additional reactions with other standard antisera.
Mi-I (Mia), Mi-II(Vw), Mi-VII and Mi-VIII are carried on glycophorin A. Mi-I is due to a mutation at amino acid 28 (threonine to methionine: C→T at nucleotide 83) resulting in a loss of the glycosylation at the asparagine26 residue. [13] [14] Mi-II is due to a mutation at amino acid 28 (threonine to lysine:C->A at nucleotide 83). [14] Similar to the case of Mi-I this mutation results in a loss of the glycosylation at the asparagine 26 residue. This alteration in glycoslation is detectable by the presence of a new 32kDa glycoprotein stainable with PAS. [15] Mi-VII is due to a double mutation in glycophorin A converting an arginine residue into a threonine residue and a tyrosine residue into a serine at the positions 49 and 52 respectively. [16] The threonine-49 residue is glycosylated. This appears to be the origin of one of the Mi-VII specific antigens (Anek) which is known to lie between residues 40-61 of glycophorin A and comprises sialic acid residue(s) attached to O-glycosidically linked oligosaccharide(s). This also explains the loss of a high frequency antigen ((EnaKT)) found in normal glycophorin A which is located within the residues 46–56. Mi-VIII is due to a mutation at amino acid residue 49 (arginine->threonine). [17] M-VIII shares the Anek determinant with MiVII. [18] Mi-III, Mi-VI and Mi-X are due to rearrangements of glycophorin A and B in the order GlyA (alpha)-GlyB (delta)-GlyA (alpha). [19] Mil-IX in contrast is a reverse alpha-delta-alpha hybrid gene. [20] Mi-V, MiV(J.L.) and Sta are due to unequal but homologous crossing-over between alpha and delta glycophorin genes. [21] The MiV and MiV(J.L.) genes are arranged in the same 5' alpha-delta 3' frame whereas Sta gene is in a reciprocal 5'delta-alpha 3' configuration.
The incidence of Mi-I in Thailand is 9.7%. [22]
Peptide constructs representative of Mia mutations MUT and MUR have been attached onto red blood cells (known as kodecytes) and are able to detect antibodies against these Miltenberger antigens [23] [24] [25]
Although uncommon in Caucasians (0.0098%) and Japanese (0.006%), the frequency of Mi-III is exceptionally high in several Taiwanese aboriginal tribes (up to 90%). In contrast its frequency is 2-3% in Han Taiwanese (Minnan). The Mi-III phenotype occurs in 6.28% of Hong Kong Chinese. [26]
Mi-IX (MNS32) occurs with a frequency of 0.43% in Denmark. [27]
Stones (Sta) has been shown to be the product of a hybrid gene of which the 5'-half is derived from the glycophorin B whereas the 3'-half is derived from the glycophorin A. Several isoforms are known. This antigen is now considered to be part of the Miltenberger complex.
A related antigen is Sat. This gene has six exons of which exon I to exon IV are identical to the N allele of glycophorin A whereas its 3' portion, including exon V and exon VI, are derived from the glycophorin B gene. The mature protein SAT protein contains 104 amino acid residues.
Orriss (Or) appears to be a mutant of glycophorin A but its precise nature has not yet been determined. [28]
The Mg antigen is carried on glycophorin A and lacks three O-glycolated side chains. [29]
Osa (MNS38) is due to a mutation at nucleotide 273 (C->T) lying within exon 3 resulting in the replacement of a proline residue with a serine. [30]
Nya (MNS18) is due to a mutation at nucleotide 194 (T->A) which results in the substitution of an aspartate residue with a glutamate. [30]
Anti-M although occurring naturally has rarely been implicated in transfusion reactions. Anti-N is not considered to cause transfusion reactions. Severe reactions have been reported with anti-Miltenberger. Anti Mi-I (Vw) and Mi-III has been recognised as a cause of haemolytic disease of the newborn. [31] Raddon has been associated with severe transfusion reactions. [32]
The Wright b antigen (Wrb) is located on glycophorin A and acts as a receptor for the malaria parasite Plasmodium falciparum . [33] Cells lacking glycophorins A (Ena) are resistant to invasion by this parasite. [34] The erythrocyte binding antigen 175 of P. falciparum recognises the terminal Neu5Ac(alpha 2-3)Gal-sequences of glycophorin A. [35]
Several viruses bind to glycophorin A including hepatitis A virus (via its capsid), [36] bovine parvovirus, [37] Sendai virus, [38] influenza A and B, [39] group C rotavirus, [40] encephalomyocarditis virus [41] and reoviruses. [42]
Glycophorin C plays a functionally important role in maintaining erythrocyte shape and regulating membrane material properties, possibly through its interaction with protein 4.1. Moreover, it has previously been shown that membranes deficient in protein 4.1 exhibit decreased content of glycophorin C. It is also an integral membrane protein of the erythrocyte and acts as the receptor for the Plasmodium falciparum protein PfEBP-2.
Duffy antigen/chemokine receptor (DARC), also known as Fy glycoprotein (FY) or CD234, is a protein that in humans is encoded by the ACKR1 gene.
Complement receptor type 1 (CR1) also known as C3b/C4b receptor or CD35 is a protein that in humans is encoded by the CR1 gene.
CD36, also known as platelet glycoprotein 4, fatty acid translocase (FAT), scavenger receptor class B member 3 (SCARB3), and glycoproteins 88 (GP88), IIIb (GPIIIB), or IV (GPIV) is a protein that in humans is encoded by the CD36 gene. The CD36 antigen is an integral membrane protein found on the surface of many cell types in vertebrate animals. It imports fatty acids inside cells and is a member of the class B scavenger receptor family of cell surface proteins. CD36 binds many ligands including collagen, thrombospondin, erythrocytes parasitized with Plasmodium falciparum, oxidized low density lipoprotein, native lipoproteins, oxidized phospholipids, and long-chain fatty acids.
The ABO blood group system is used to denote the presence of one, both, or neither of the A and B antigens on erythrocytes. For human blood transfusions, it is the most important of the 44 different blood type classification systems currently recognized by the International Society of Blood Transfusions (ISBT) as of December 2022. A mismatch in this, or any other serotype, can cause a potentially fatal adverse reaction after a transfusion, or an unwanted immune response to an organ transplant. The associated anti-A and anti-B antibodies are usually IgM antibodies, produced in the first years of life by sensitization to environmental substances such as food, bacteria, and viruses.
α-Galactosidase is a glycoside hydrolase enzyme that catalyses the following reaction:
A glycophorin is a sialoglycoprotein of the membrane of a red blood cell. It is a membrane-spanning protein and carries sugar molecules. It is heavily glycosylated (60%). Glycophorins are rich in sialic acid, which gives the red blood cells a very hydrophilic-charged coat. This enables them to circulate without adhering to other cells or vessel walls.
Animal erythrocytes have cell surface antigens that undergo polymorphism and give rise to blood types. Antigens from the human ABO blood group system are also found in apes and Old World monkeys, and the types trace back to the origin of humanoids. Other animal blood sometimes agglutinates with human blood group reagents, but the structure of the blood group antigens in animals is not always identical to those typically found in humans. The classification of most animal blood groups therefore uses different blood typing systems to those used for classification of human blood.
The MNS antigen system is a human blood group system based upon two genes on chromosome 4. There are currently 50 antigens in the system, but the five most important are called M, N, S, s, and U.
P1PK is a human blood group system based upon the A4GALT gene on chromosome 22. The P antigen was first described by Karl Landsteiner and Philip Levine in 1927. The P1PK blood group system consists of three glycosphingolipid antigens: Pk, P1 and NOR. In addition to glycosphingolipids, terminal Galα1→4Galβ structures are present on complex-type N-glycans. The GLOB antigen is now the member of the separate GLOB blood group system.
Krueppel-like factor 1 is a protein that in humans is encoded by the KLF1 gene. The gene for KLF1 is on the human chromosome 19 and on mouse chromosome 8. Krueppel-like factor 1 is a transcription factor that is necessary for the proper maturation of erythroid cells.
NADH-cytochrome b5 reductase 3 is an enzyme that in humans is encoded by the CYB5R3 gene.
Galactoside 3(4)-L-fucosyltransferase is an enzyme that in humans is encoded by the FUT3 gene.
Blood group Rh(CE) polypeptide is a protein that in humans is encoded by the RHCE gene. RHCE has also recently been designated CD240CE.
Glycophorin B (MNS blood group) (gene designation GYPB) also known as sialoglycoprotein delta and SS-active sialoglycoprotein is a protein which in humans is encoded by the GYPB gene. GYPB has also recently been designated CD235b (cluster of differentiation 235b).
Ecto-ADP-ribosyltransferase 4 is an enzyme that in humans is encoded by the ART4 gene. ART4 has also been designated as CD297.
Glycophorin-E is a protein that in humans is encoded by the GYPE gene.
Rh blood group, D antigen also known as Rh polypeptide 1 (RhPI) or cluster of differentiation 240D (CD240D) is a protein that in humans is encoded by the RHD gene.
The Sid blood group system is a human blood group defined by the presence or absence of the Sd(a) antigen on a person's red blood cells. About 96% of people are positive for the Sd(a) antigen, which is inherited as a dominant trait. Among Sd(a) positive individuals, the expression of the antigen ranges from extremely weak to extremely strong. Very strong expression of the antigen is referred to as a Sd(a++) phenotype. In addition to being expressed on red blood cells, Sd(a) is secreted in bodily fluids such as saliva and breast milk, and is found in the highest concentrations in urine. Urine testing is considered the most reliable method for determining a person's Sid blood type.
Elwira Lisowska is a Polish biochemist and professor. She made significant contributions to the biochemistry of human blood groups, especially MNS and P1PK blood group systems, and to the immunochemical characterization of glycopeptide antigens.
This article incorporates text from the United States National Library of Medicine, which is in the public domain.