This peptide is derived from the C-terminus of the chemokine, complement fragment 5 anaphylatoxin (C5a). This peptide functions as a C5a receptor agonist. C5a is a plasma protein involved in cellular inflammatory processes by inducing chemotaxis, degranulation of leukocytes, increased vascular permeability, and cytokine production. The cyclohexylalanine at position 5 is crucial to agonist function. Arg at the last position is of the d-isomer.