Figure 3: Amino acid sequences and phylogenetic organization of
Kunitz toxins. (A) Sequence alignment according to the MQ1
sequence. Greek letters indicate MQ1 secondary structures, α for alpha
helix, β for beta strain. Arabic numbers design MQ1 loops, loop 1 from
residue 7 to 20, loop 2 from residue 32 to 49, loop 3 from residue 25 to
29. Red: toxins from Mamba active on V2R. Green: toxins from cobra
active on V2R. Blue: toxins from Mamba active on Kv1.1. Pink: toxins
from Mamba active on Cav. Orange: BPTI. Black: Unknown activities.
Underline names: peptides not active on V2R. Bold residues are different
from MQ1. MQ1 red residues are specific for V2R Kunitz-type peptides.
Calci: calcicludine P81658. BPTI: Bovine Pancreatic Trypsin Inhibitor.
Id: percentage of sequence identity to MQ1. (B) Maximum
likelihood (ML) tree of MQ proteins and related sequences obtained with
RAxML. Branches with at least three sequences were annotated with the
average frequency of ML tree bipartition among the 3000 trees with best
posterior probabilities for each one of three chains of a MrBayes 3.2.6
run (top 1000 per run). Average bipartition frequency: 0.5-0.7, white
circles; 0.7-0.9 grey circles; 0.9-1.0 black circles. Sequences in the
alignment of panel A are highlighted in bold characters. Scale bar
represents substitutions per site. Protein identifiers follow the same
color scheme as panel A.