Glycomics
See Also
Description
The major sialoglycoprotein of the human erythrocyte membrane. It consists of at least two sialoglycopeptides and is composed of 60% carbohydrate including sialic acid and 40% protein. It is involved in a number of different biological activities including the binding of MN Blood Group, influenza viruses, kidney bean phytohemagglutinin, and wheat germ agglutinin.
Glycophorin A
Glycophorin A is a [Glycoprotiens? glycoprotein] that spans the plasma membrane (lipid bilayer) of human red blood cells. Each RBC has some 500,000 copies of the molecule embedded in its plasma membrane.
Two polymorphic versions of glycophorin A, which differ only at residues 1 and 5, occur in humans. These give rise to the MN blood groups:
- The M allele encodes Ser at position 1 (Ser-1) and Gly at position 5 (Gly-5)
- The N allele encodes Leu-1 and Glu-5
- Individuals who inherit two N alleles have blood group N.
- Individuals who are homozygous for the M allele have blood group M.
- Heterozygous individuals produce both proteins and have blood group MN.
Glycophorin A is the most important attachment site by which the parasite Plasmodium falciparum invades human red blood cells.
Glycophorins C and D
Glycophorin C and D encode the Gerbich (Ge) antigens which were described in 1960 and are named after one of the three original patients. There are four allelles, Ge-1 to Ge-4. Three types of Ge antigen negativity are known: Ge-1,-2,-3 (Leach phenotype), Ge-2,-3 and Ge-2,+3. A 3.4 kilobase pair deletion within the gene, which probably arose because of unequal crossing over between the two repeated domains, is responsible for the formation of the Ge-2,-3 genotype. The breakpoints of the deletion are located within introns 2 and 3 and results in the deletion of exon 3.
Glycophorin C (GYPC; CD236/CD236R; glycoprotein beta; glycoconnectin; PAS-2') is an integral membrane protein of the erythrocyte and acts as the receptor for the Plasmodium falciparum protein PfEBP-2 (erythrocyte binding protein 2; baebl; EBA-140).[1]
Other database IDs and links
NCBI genes
Uniprot ID
Genbank proteins
Gene nomenclature database ID
Genbank nucleic acids
NCBI homologenes for homologs and orthologs
NCBI dbSNP for single nucleotide polymorphisms
HGMD ID - at the Human Gene Mutation Database
OMIM ID - at Online Mendelian Inheritance in Man
Attribution
- This article is licensed under the GNU Free Documentation License. Sections excerpted from Blood Group Antigen Gene Mutation Database. See: Blumenfeld OO, Patnaik SK. Allelic genes of blood group antigens: a source of human mutations and cSNPs documented in the Blood Group Antigen Gene Mutation Database. Human Mutation. 2004 Jan; 23(1):8-16. PubMed ID: 14695527
