Comparison of hydrophobicity between latherin and human PLUNC family members.

Amino acid sequences were obtained for horse latherin (NP_001075328) as well as the human LT/LBP family members BASE (AAO17728.1), PLUNC (also known as SPLUNC1) (NP_057667), SPLUNC2 (NP_542141), SPLUNC3 (NP_848561.2), BPI (NP_001716.2), and LBP (NP_004130.2). The analyses for SP-B and SP-C were based on the mature, proteolytically processed peptides for each, as described in [57]. To determine percent sequence identity with latherin, protein-protein BLAST (bl2seq) was performed to align latherin with each of the short PLUNC family members; for BPI and LBP, the sequence homology with latherin was so low that alignments could not be made (not done = “ND”). For the calculation of percent total hydrophobic residues, the amino acids isoleucine, valine, leucine, phenylalanine, cysteine, methionine, and alanine were considered to be the hydrophobic residues, based on the hydropathy index developed by Kyte and Doolittle [58]. The GRAVY (grand average of hydropathicity) value represents the sum of the hydropathy values for each amino acid in a protein, divided by the total number of residues. A protein with calculated GRAVY >0 is hydrophobic, while a GRAVY