Primary sequence data obtained from the 5′ untranslated region of the V_H1 gene rearrangement of L1236 cells. The V_H1 gene rearrangement was amplified using the oligonucleotide 21-2UIS hybridizing to the 5′ region of the V_H1 gene rearrangement and the oligonucleotide 3H1 hybridizing to the CDRIII of the V_H1 gene rearrangement. Sequencing was performed using the VH1LAS oligonucleotide hybridizing to the leader region resulting in the antisense sequence. The sequence is given above. Numbers indicate the nucleotide positions on the gel. Note that the first position (number 182) of the octamer (number 175 until number 182) is mutated (A→T; for comparison with germline sequence, see also Fig 6).