hCAP18, the only cathelicidin gene found in humans
In humans, cathelicidins and defensins are expressed in immune cells and at epithelial surfaces.
hCAP18 is the human cationic antimicrobial protein, with a MW of 18 kD.
The N-terminus of this protein consists of a cathelin-like region (highly conserved among species) and a C-terminal termed LL-37.
An amphipathic alpha-helical peptide, LL-37 plays an important role in the first line of defense against local infection and systemic invasion of pathogens at sites of inflammation and wounds.
Cathelicidins have broad-range antimicrobial activity
Cytotoxic to both bacterial and normal eukaryotic cells, LL-37 is significantly resistant to proteolytic degradation in solution. In addition to having antimicrobial activity, LL-37 has been shown to play a role in chemoattraction, dendritic cell differentiation, mast cell degranulation, cytokine secretion, angiogenesis stimulation, and wound healing.
In other species, the C-terminal antimicrobial region varies in size, sequence and structure.
Cathelicidins are cationic peptides belonging to the family of antimicrobial peptides which form part of the host's important innate immunity mechanism.