IGHV sequence alignments related to Fig. 4, D and E . (A) Alignment of the amino acid sequences of IGHV3-15 and IGHV3-74 according to the IMGT numbering. The conserved R residue in position 55 is highlighted in blue and with an arrow. Positions that differ between the two gene segments are shown in red. (B) Alignment of the amino acid sequences of IGHV4-4*01 and IGHV4-4*07 according to the IMGT numbering. The polymorphic R/E residue in position 55 is highlighted in blue and with an arrow. Other residues that differ between the two alleles are shown in red.