Annexin

Annexin is a common name for a group of cellular proteins. They are mostly found in eukaryotic organisms (animal, plant and fungi).

In humans, the annexins are found inside the cell. However some annexins (Annexin A1, Annexin A2, and Annexin A5) have also been found outside the cellular environment, for example, in blood. How the annexins are transported out of the cell into the blood is a mystery because they lack a signal peptide necessary for proteins to be transported out of the cell.