Similarity between the CLLU1-encoded protein and IL-4. (A) Alignment of the peptide sequences of CLLU1 and IL-4 from bovine and human. Residues that are similar in their physiochemical properties in all 3 sequences are colored according to hydrophobic (white on black), aromatic (blue on gray), aliphatic (red on gray), polar (black on green), amphoteric (red on green), charged (white on blue), negative (green on blue), positive (red on blue), small (green on yellow), tiny (blue on yellow), glycine (yellow on red), and proline (blue on red). An asterisk indicates residues that are identical in all 3 sequences; +, residues that are conserved in CLLU1 and either bovine or human IL-4. The arrow indicates the position where the signal peptide is cleaved in human and bovine IL-4, and the extent of the 4 α-helixes is shown below the sequences. (B) Three-dimensional structure of human IL-4 (left) and the theoretic CLLU1 structure (right). The 4 α-helices are labeled A, B, C, and D.