Fig. 5.

cDNA-encoded precursor sequences of Q-superfamily conotoxins identified in this work. A, alignment of the precursor sequences of the Q-conotoxins shows that their mature toxins may have different lengths and different cysteine frameworks. The conserved signal peptide is shaded in gray. The mature peptide regions of Fla16.1 and Qc16.1 are underlined. B, comparison of the cDNA and protein sequences of Fla16.5 and Fla6.18 shows that the alteration in the length and cysteine framework of the Q-conotoxins is caused by a single nucleotide change in the cDNA sequence, which leads to the premature termination of the encoding region.