Comparison of rhesus and human cathelicidin peptides. Both signal peptides (underlined) have 30 residues, of which 28 (93.3%) are identical. Both cathelin domains have 101 residues, of which 93 (92%) are identical. The mature domains (dotted underlined) of RL-37 and LL-37 both contain 37 residues, of which 25 (67.6%) are identical. Mature rhesus RL-37 has a mass of 4,100.9 Da, a theoretical pI of 11.20, and a net charge of +8. Mature human LL-37 has a mass of 4527.34, a pI of 10.61, and a net charge of +6. A vertical line connects identical residues, and a plus sign identifies conservative substitutions. Residues that differ in the human and rhesus peptides are shown in boldface type.