FIGURE 1.

α-Conotoxin TxIB prepropeptide and encoded toxin are shown. A putative proteolytic processing site 1 (R) and amidated processing sites 2 and 3 are indicated by arrows. The pro-region is italics. The mature toxin region is underlined. The first and second glycine following the C-terminal cysteine in the mature toxin is presumed to be processed to a C-terminal amide for α-CTx TxIB and α-CTx TxIB(G), respectively. TxIB(G) is an analog of TxIB with an extra G (TxIB(G)). The cysteine residues are indicated in bold. The stop codon is indicated by the ♦. The deduced mature toxin sequence of TxIB is GCCSDPPCRNKHPDLC# (# = C-terminal carboxamide).