Amino acid sequence alignment of mouse and humanized LM609. Shown are FRs and CDRs. Dashes indicate identical amino acids. Note that due to our grafting procedure CDR3 is identical in the original mouse and the selected human sequences. (A) Alignment of the selected human VL sequences. Databank screening revealed that the two selected human VL sequences are derived from germ-line DPK-26 of the Vκ3 family. (B) Alignment of the selected human VH sequences. Five different human VH sequences were selected. Four of them, represented by clones 7, 4, 24, and 2, are highly related in amino acid sequence; they share an identical VL domain and an amino acid sequence identity of at least 85% in their VH domains. The VH sequences are all derived from germ-line DP-65 or the highly related DP-78. In contrast, clone 11 represents a humanized version with a VH domain that is derived from a different germ-line family. This humanized version also contains a different VL domain which is 96% identical and derived from the same germ-line. Germ-lines were determined by nucleic acid sequence alignment using DNAPLOT software provided by the VBASE Directory of Human V Gene Sequences (http://www.mrc-cpe.cam.ac.uk/imt-doc/). 1clone 11, germ-line DPK-26 (Vκ6 family); 2clones 2, 4, 7, 24, germ-line DPK-26 (Vκ6 family); 3clone 11, germ-line DP-10 (VH1 family); 4clone 7, germ-line DP-78 (VH4 family); 5clone 4, germ-line DP-65 (VH4 family); 6clone 24, germ-line DP-65 (VH4 family); 7clone 2, germ-line DP-65 (VH4 family).