PPBP Gene: Pro-Platelet Basic Protein – Function, Mutations, and Disease Associations

PPBP (pro-platelet basic protein) encodes a member of the CXC chemokine family. The protein is synthesized in megakaryocytes and stored in platelet alpha-granules. Upon platelet activation, it is proteolytically processed into several active peptides, including platelet basic protein (PBP), connective tissue-activating peptide III (CTAP-III), beta-thromboglobulin (beta-TG), and neutrophil-activating peptide 2 (NAP-2). These peptides have chemotactic, mitogenic, and inflammatory activities, particularly attracting and activating neutrophils, and promoting fibroblast proliferation and angiogenesis.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Chemokine signaling pathway (KEGG: hsa04062)

• Cytokine-cytokine receptor interaction (KEGG: hsa04060)

• IL-17 signaling pathway (KEGG: hsa04657)

• TNF signaling pathway (KEGG: hsa04668)

The PPBP protein (UniProt P02775) is a 128-amino-acid precursor that undergoes sequential proteolytic cleavage to generate multiple bioactive peptides. The full-length protein is known as platelet basic protein (PBP). Cleavage by cathepsin G or chymotrypsin yields connective tissue-activating peptide III (CTAP-III; residues 44-128). Further N-terminal truncation by neutrophil proteases produces beta-thromboglobulin (beta-TG; residues 45-128) and neutrophil-activating peptide 2 (NAP-2; residues 59-128). NAP-2 is a potent chemoattractant and activator of neutrophils via CXCR2. The protein also promotes fibroblast proliferation, collagen synthesis, and angiogenesis.