Glycophorin
# Glycophorin

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.

