P-selectin

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P-selectin was originally described as the 789 amino-acid processed fragment [42 – 830] of the 830 amino-acid P-selectin precursor protein and is coded for by the SELP gene at 1q23-q25. It acts as an Ca2+-dependent receptor adhesion molecule. Expression is on the external membrane surface of activated endothelial cells or platelets where it is stored in stored in the Weibel-Palade bodies and α-granules respectively until activation. It then mediates interactions with leukocytes. Structurally it has regions for protein and sugar binding. P-selectin glycoprotein ligand-1 is the most important ligand on myeloid cells and stimulated T lymphocytes in this key interaction. Another recognised ligand on neutrophils and monocytes is the blood group antigen sialyl-Lewis X which also interacts with E-selectin and it also binds to CD24 which is expressed in small cell lung malignancy and may have a role in metastatic dissemination.

A fragment [1-138] of P-selectin precursor protein which contains the initial signal peptide and C-type lectin domain has also been described in biological systems. The active signalling part that interacts with cytosol sorting nexin 17 is coded at [821 – 830].

An antibody crizanlizumab is in development, initially for the indication of sickle cell disease.

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