Alpha-defensin propeptide (IPR016327)

Short name: Alpha-defensin_pro

Overlapping homologous superfamilies


Family relationships



Mammalian alpha-defensins are expressed primarily in leukocytes and epithelia. They play an important role in the innate and adaptive immune response to microbial infection. There are six cysteine residues and one glycine residue, for an atypical SS-bulge, which are totally conserved in the otherwise diverse sequences of all known mammalian alpha-defensins. There is also a conserved pair of oppositely charged residues (Arg/Glu) that form a salt bridge across a protruding loop in the molecule. The primary function of the salt bridge in HD5 is to ensure correct processing of proHD5 and subsequent stabilisation of mature alpha-defensin in vivo [PMID: 18499668].

Human neutrophil alpha-defensins (HNPs) are synthesized in vivo as inactive precursor proteins, i.e. preproHNPs. A series of sequential proteolytic events excise the N-terminal inhibitory pro peptide, leading to defensin maturation and storage in azurophilic granules [PMID: 17355880]. Human alpha-defensin-1 (HNP1) is a small antimicrobial peptide, which is cytotoxic to tumour cells in vitro and shows inhibitory activity for pathologic neovascularisation in vivo. Intracellularly expressed HNP1 induces tumour cell apoptosis, consequently inhibiting its growth. It might be involved in the host immune response to tumours and as such is a promising basis for HNP1-based gene therapy for cancer [PMID: 18566229].

GO terms

Biological Process

GO:0006952 defense response

Molecular Function

No terms assigned in this category.

Cellular Component

GO:0005615 extracellular space

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.