CTNNB1: taxonomic census of the beta-catenin family (UniProt)
Script: taxon_census.py (stdlib only, UniProt REST API). Raw output: census_output.txt
(run 2026-10-01).
Question
Is the beta-catenin family (as defined by PANTHER PTHR45976 "ARMADILLO SEGMENT
POLARITY PROTEIN", which contains human CTNNB1 as PTHR45976:SF4, and InterPro
IPR013284 "Beta-catenin") found outside animals, in particular in the unicellular
holozoans (choanoflagellates, filastereans, ichthyosporeans) or in Dictyostelium?
Results
| Classification |
Metazoa |
non-Metazoa |
Choanoflagellata |
Filasterea |
Ichthyosporea |
Dictyostelium |
| PANTHER PTHR45976 |
4921 |
2 |
0 |
0 |
0 |
0 |
| InterPro IPR013284 |
4937 |
3 |
0 |
0 |
0 |
0 |
- The two non-metazoan PTHR45976 entries are single proteins from land-plant
genome assemblies (Sphagnum jensenii A0ABP0VBH0, Olea europaea A0A8S0TRJ0).
No other plant has one, so these are most likely contaminating animal sequences in
the assemblies; this was not tested here.
- The extra IPR013284 entry is a chytrid "Vacuolar protein 8" (A0A139A5K2) that
PANTHER puts in a different family (PTHR47249), so the InterPro signature
picks up an unrelated ARM protein here.
- Dictyostelium Aardvark (Q54I71), the "beta-catenin homologue" of
PMID:11130075, is placed by PANTHER in PTHR22895 "ARMADILLO REPEAT-CONTAINING
PROTEIN 6", not in the beta-catenin family.
Interpretation (limits)
- By current HMM classifications, the beta-catenin family is restricted to animals,
with no members in choanoflagellates, Capsaspora or ichthyosporeans. This agrees
with gene-family reconstructions that list catenin beta as an animal-specific family
(PMID:29848444).
- Aardvark is an armadillo-repeat protein that works with a Dictyostelium
alpha-catenin ortholog (PMID:21393547). Database classification does not put it
in the beta-catenin family. Whether it is a divergent ortholog, an older ARM
paralog, or a convergent junction protein would need a proper phylogeny of
ARM-repeat proteins, which was not done here.
- These are classification counts, not a phylogeny. A beta-catenin-like gene that
is missing from UniProt or classified elsewhere would not be detected.