Table 3.

Molecular phylogeny of G. lamblia

GenePhylogenetic positionReference(s)
SS (18S) rRNAAt base of tree with T. vaginalis and microsporidia or long-branch artifact308, 315
Translational apparatus
 RNA polymerase IIILater; similar to T. brucei175
 EF1-alphaEarly divergence; diplomonads form a single clade or long-branch attraction artifact125, 133, 157
 EF2Early divergence or long-branch attraction artifact124, 133
 Eukaryotic release factor 1 (eRF1)Basal142
 Eukaryotic release factor 3 (eRF3)Early divergence142
 RNA polymerase II large subunit (RPB1)Position cannot be determined because of long-branch attraction artifact133
Transcription apparatus
Mitochondrial genes
 cpn60Basal along withT. vaginalis and E. histolytica107, 286
 Valyl-tRNA synthetaseSecondary lack of mitochondria; related to gamma-proteobacteria; branches withArabidopsis126
 AnnexinsAlpha-giardins as primitive annexins232
 ActinEarly divergence67
 β-TubulinLater divergence than E. histolytica71, 345
Metabolic pathways
 Triosephosphate isomeraseEubacterial (alpha-proteobacteria) origin, unweighted parsimony putsGiardia at base158
 Glutamate dehydrogenase (NADP dependent)Possibly of eubacterial origin22, 272, 359
 Adenylate kinaseImpossible to resolve order of emergence288
 Glyceraldehyde-3-phosphate dehydrogenaseMonophyletic with other diplomonads; later divergence287
 Pyruvatephosphate dikinaseNo evidence for early divergence255, 289
 Malate dehydrogenaseEukaryotic, related to T. vaginalis285
 Malate dehydrogenase, decarboxylatingPosition cannot be adequately resolved294
 Fructose-1,6-bisphosphate aldolase (class II)Similar to eubacteria128
 Acetyl-CoA synthetaseNo evidence for early divergence293
Other genes
 Cathepsin B (cysteine protease)Early divergence344
 Signal recognition peptideEukaryotic with some bacterial and archael features321
 HSP70 (cytosolic and GRP78/BiP)Giardia at base, before T. vaginalis; similarities to eubacteria107, 121
 CDC2 (member of cyclin-dependent kinase  family)Early branching, but after E. histolytica andT. vaginalis284