Biology:Glycophorin

Glycophorin A
Dimeric transmembrane domain of human glycophorin A (20 NMR-determined structures)
Identifiers
Symbol	GYPA
Pfam	PF01102
InterPro	IPR001195
PROSITE	PDOC00281
SCOP2	1afo / SCOPe / SUPFAM
OPM superfamily	25
OPM protein	5eh4
Membranome	156
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

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.

A particular mutation in Glycophorins is thought to produce a 40% reduction in risk of severe malaria.

Identification

After separation of red cell membranes by SDS-polyacrylamide gel electrophoresis and staining with periodic acid-Schiff staining (PAS), four glycophorins have been identified. These have been named glycophorin A, B, C, and D in order of the quantity present in the membrane, gylycophorin A being the most and glycophorin D the least common. A fifth (glycophorin E) has been identified within the human genome but cannot easily be detected on routine gel staining. In total, the glycophorins constitute ~2% of the total erythrocyte membrane protein mass. These proteins are also known under different nomenclatures but they are probably best known as the glycophorins.

Family members

The following four human genes encode glycophorin proteins:

• Glycophorin A
• Glycophorin B
• Glycophorin C
• Glycophorin E

Glycophorin D is now known to be a variant of Glycophorin C.

External links

• Glycophorin at the US National Library of Medicine Medical Subject Headings (MeSH)
• UMich Orientation of Proteins in Membranes protein/pdbid-1afo