Members of the defensin family are highly similar in protein sequence and distinguished by a conserved cysteine motif.

The protein encoded by this gene, defensin, alpha 1, is found in the microbicidal granules of neutrophils and likely plays a role in phagocyte-mediated host defense.

[6][7] Cationic 29-30 amino acids HNPs associate with the negatively charged proteoglycan serglycin and translocate to azurophil granules.

[8] At later stages of granulocytic differentiation in which HNP expression peaks (i.e. myelocytes and metamyelocytes), proHNPs are not cleaved, rendering the peptides overall neutral.

This prevents binding to serglycin and most proHNP is accordingly secreted into the bone marrow plasma although some is retained in specific granules.