Fig. 4. Unrooted phylogenetic tree of the myosin superfamily. Head domains of 40 myosin proteins available from public data bases were aligned to amino acids 213–511 of the chicken fast skeletal myosin (Gg FSK), a class II myosin, using the default CLUSTAL method settings (Lasergene/DNASTAR). The PHYLIP phylogeny package (http://evolution. genetics.washington.edu/phylip.html) (Felsenstein, 1993) was used to generate a genetic distance tree; 1000 bootstrap data sets were generated and analyzed with the programs PROTDIST and NEIGHBOR. The programs CONSENSE, FITCH, and DRAWTREE were used to produce the unrooted distance tree. The frequency of node placement for 1000 bootstrap trials is indicated as >90, >70, and >50% by solid circles, gray circles, and open circles, respectively. Sequence divergence is proportional to the length of the branches. The length of the bar equals 5% sequence divergence. Myosin classes are indicated by Roman numerals. The species represented areAcanthamoeba castellanii (Aca),Acetabularia cliftonii (Acl),Arabidopsis thaliana (At), Brugia malayi (Bm), Bos taurus(Bt), Caenorhabditis elegans(Ce), Dictyostelium discoidium(Dd), Drosophila melanogaster(Dm), Gallus gallus (Gg),Helianthus annus (Ha), Homo sapiens (Hs), Mus musculus(Mm), Plasmodium falciparum(Pf), Rattus norvegicus(Rn), Saccharomyces cerevisiae(Sc), Sus scrofa (Ss), andToxoplasma gondii (Tox). The GenBank accession numbers for the sequences by class are as follows—class I: Dd MIA (P22467), Dm MIA (S45573), Gg BBMI (U04049), MmIA (L00923), Rn myr 1a (X68199), Rn myr 2 (X74800), Rn myr 3 (X74815), Rn myr 4 (X71997); class II: Bm II (M74000), Dd II (p08799), Dm NM2 (P05661), Gg Fsk (P13538), Sc myo1(IIA) (S46773); class III: Dm Nina C (p10676); class IV: Aca HMW (j05678); class V: Gg p190 (z11718), Mm dilute (x57377), Rn myr 6 (u60416), Sc myo2 (VA) (p19524), Sc myo4 (VB) (p32492); class VI: Dm 95F (Q01989), Mm Snell's waltzer (u49739), Ss VI (a54818); class VII: Hs VIIa (u55208), Mm shaker-1 (U81453); class VIII: At ATM A (x67104), At ATM B (z34292), Ha my1 (U94781); class IX: Hs MIXb (u42391), Rn myr 5 (x77609), Rn myr 7 (AJ001713); class X: Bt X (U55042); class XI: At mya1 (z29389), At mya2 (z34294); class XII: Ce XII (z66563); class XIII: Acl M1 (U94397), Acl M2 (U94398); class XIV: Tox A (af006626), Tox B (af006627), Pf XIV (y09693); class XV: Mm myo15 (AF053130); class XVI: Rn myr 8 (AF209114).