Cloning method used to construct the supervectors by combining the light chain and heavy chain expression vectors. (a) EcoRI restriction sites in recombinant light chain expression vector, pLN10, containing Vλ cloned DNA sequences. (b) EcoRI-digested light chain cassette containing human cytomegalovirus (HCMV) promoter, immunoglobulin leader sequence, light chain variable-region DNA sequence, and constant-region DNA sequence. (c)Ligation of light chain cassette into EcoRI-linearised B3VH/pG1D1 heavy chain vector to produce the final supervector, containing all components required to produce whole IgG1. The four supervectors were constructed in the same way, using the appropriate EcoRI-digested light chain fragments leading to slight variations in the overall plasmid size. SV40, simian virus 40; V:C, variable : constant.