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FB2025_04
,
released October 2, 2025
β-catenin, β-cat, beta-catenin, b-catenin, βcatenin
plakoglobin and beta catenin homolog - functions in transducing signals from the Wingless/Wnt family of proteins and works with cadherins to mediate cell adhesion - Wingless target genes are activated when stabilized Armadillo enters the nucleus and recruits other coactivators to the target loci through TCF/Pangolin
Please see the JBrowse view of Dmel\arm for information on other features
To submit a correction to a gene model please use the Contact FlyBase form
AlphaFold produces a per-residue confidence score (pLDDT) between 0 and 100. Some regions with low pLDDT may be unstructured in isolation.
Alternative translation stop created by use of multiphasic reading frames within coding region.
Variable use of small exon; supported combination results in frameshift and premature stop in downstream exon.
Annotated transcripts do not represent all possible combinations of alternative exons and/or alternative promoters.
Low-frequency RNA-Seq exon junction(s) not annotated.
Annotated transcripts do not represent all supported alternative splices within 5' UTR.
Gene model reviewed during 5.45
Gene model reviewed during 5.55
721 (aa); 105-115, 82 (kD observed)
843 (aa); 93 (kD)
91 (kD)
arm protein is phosphorylated on both serine or threonine and on tyrosine residues. The level of phosphorylation varies in different tissues and at different times of development. Phosphorylation of arm protein is negatively regulated by wg protein. sgg protein is required for arm protein phosphorylation.
The majority of arm protein in vivo is part of a membrane-associated complex containing α-Cat and an unidentified glycoprotein.
Antibodies raised against arm protein recognize a single protein in canine (MDCK), mouse (3T3), African green monkey (COS-7), and Xenopus (A6) cultured cells. The cross-reacting proteins in A6 and MDCK cells were shown to be β-catenin.
Interacts with Mer and Moe at the adherens junction (PubMed:8666669). Interacts with Inx2 (PubMed:15047872). Interacts with alpha-Cat (PubMed:25653389). Interacts with Myo31DF (PubMed:16598259, PubMed:22491943).
Phosphorylated on Ser, Thr and Tyr residues (PubMed:7529201). Level of phosphorylation varies both during embryonic development and from embryonic tissue to tissue (PubMed:7529201). Sgg is required for phosphorylation and wg signal negatively regulates arm phosphorylation (PubMed:7529201). Hypophosphorylated form of arm increases in steady-state levels (PubMed:7529201). Phosphorylated directly or indirectly by CkIalpha which stimulates its degradation (PubMed:11927557).
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\arm using the Feature Mapper tool.
The testis specificity index was calculated from modENCODE tissue expression data by Vedelek et al., 2018 to indicate the degree of testis enrichment compared to other tissues. Scores range from -2.52 (underrepresented) to 5.2 (very high testis bias).
Comment: maternally deposited
The intracellular distribution of arm protein in imaginal discs, salivary glands and larval brain was described. In salivary glands, arm protein is concentrated at the junctions between cells and is punctate on the apical surface. It is uniformly distributed on the lateral surfaces. arm protein distribution is also polarized in imaginal discs where high levels are restricted to the apical side. In the embryonic CNS and larval brain, arm protein is enriched in fiber tracts and there is less in the cell bodies of neurons. In the eye disc, arm protein accumulates fairly uniformly on the membranes separating cells in the undifferentiated region. As the morphogenetic furrow passes, arm expression appears to increase. Strong protein accumulation is seen in a star-shaped pattern on membranes where cells in the precluster abut one another but not at junctions with undifferentiated cells. arm protein often colocalizes with actin.
arm protein localizes to junctions resembling vertebrate adherens junctions.
arm protein is observed outlining clusters of male germline stem cells.
In stage 13 embryos,arm protein expression is detected on the cell membrane of both somatic germline precursor cells as well as the germline cells in both males and females. This localization is concurrent with the processes of ensheathment and coalescence of the developing gonad. In stage 17 male embryos, arm protein is concentrated in the anterior of the gonad in the region corresponding to the testes hub.
Protein is detected in lateral membrane of the cellularizing embryo and is not detected apically.
The localization of arm protein often parallels the location of adherens junctions.
arm protein expression was studied during oogenesis. arm protein is asymmetrically localized within follicle cells. Within each follicle cell, it accumulates heavily on the lateral cell surface near the apical end abutting the germ cells. It is less abundant on the rest of the follicle cell-follicle cell interface. Staining is the heaviest in a band around the follicle cell near the interface between the lateral and apical surfaces. The majority of arm protein in the ovary is found in the follicle cells but it is also observed in n rse cells and in the oocyte. Accumulation is germ cells is first seen at the anterior tip of the germarium. Similar intense staining is seen at the anterior tip of the testis. As with follicle cells, arm protein accumulates near or at the cell surface of germ cells but is not concentrated at any one position along the cell-cell interface. Protein accumulation appears to be heaviest where the nurse cell-nurse cell junction abuts the overlying follicle cells. It also accumulates in the cortical region of the oocyte. arm protein accumulates differentially in different follicle cells. Polar ollicle cells show more intense arm staining.
In wghs.P embryos, the arm protein distribution is quite different from that in wild-type embryos, being evenly distributed and showing intense staining throughout the embryo. In nkd mutant embryos, the pattern is similar to that in wghs.P embryos, but two additional rows of cells in the wg-expressing half of the parasegment are seen.
arm protein localizes to the apical surfaces of cells.
JBrowse - Visual display of RNA-Seq signals
View Dmel\arm in JBrowse
1-0.2
Please Note FlyBase no longer curates genomic clone accessions so this list may not be complete
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see JBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
dsRNA made from templates generated with primers directed against this gene has been transfected into Kc cells.
dsRNA made from templates generated with primers directed against this gene profoundly reduces the wg-signaling pathway.
Nuclear localisation of arm is necessary for Wnt pathway activation.
dsRNA made from templates generated with primers directed against this gene tested in RNAi screen for effects on Kc167 and S2R+ cell morphology.
RNAi screen using dsRNA made from templates generated with primers directed against this gene causes a phenotype when assayed in Kc167 and S2R+ cells: cells become round and detached.
arm does not play a general role in inhibiting cell migration or process extension.
Membrane tethered arm cannot signal on its own, however it can function in adherens junctions.
The pan gene product can function as either an activator or a repressor of wg-responsive genes depending on the state of the wg signalling pathway and thus the availability of arm, the pan product coactivator. In the absence of arm, pan acts to repress wg responsive genes, with the gro protein acting as a corepressor.
Segment polarity gene expression is necessary for the survival of specific rows of epidermal cells.
Some of the proteins of apico-lateral junctions are required both for apico-basal cell polarity and for the signalling mechanisms controlling cell proliferation, whereas others are required more specifically in cell-cell signalling.
Adherens junctions cannot assemble in the absence of arm, leading to dramatic defects in cell-cell adhesion. Embryonic epithelial cells lose adhesion to each other, round up and apparently become mesenchymal. Mutant cells also lose their normal cell polarity. These disruptions in the integrity of the epithelia block the appropriate morphogenetic movements of gastrulation.
Yeast two-hybrid system and in vivo assays have identified a 76 amino acid region of arm that is necessary and sufficient for binding α-Cat and also that the N-terminal 258 amino acids of α-Cat interact with arm. A large region of arm, spanning six central arm repeats, is required for shg binding, whereas only 41 amino acids of shg are sufficient for arm binding.
Tethered arm has autonomous effects on the transcription of target genes.
The arm product has a role in cell-cell adhesion, gastrulation and epithelial sheet integrity.
The arm locus encodes a truncated 82kD isoform specific to the nervous system.
arm mutants display a disrupted actin cytoskeleton.
Comparisons of early development to that in other insects have revealed conservation of some aspects of development, as well as differences that may explain variations in early patterning events.
Cells alter their intracellular distribution of arm protein in response to wg signal, accumulating increased levels of cytoplasmic arm relative to those of membrane-associated protein. Levels of cytoplasmic arm are also regulated by sgg. Double mutant analysis demonstrates that arm's role in wg signalling is direct and that arm functions downstream of wg and sgg.
Cell culture assay of wg and arm gene expression demonstrates that the wg protein does not affect the rate of arm protein synthesis but presence of the wg protein causes increased stability of an otherwise rapidly decaying arm protein. wg protein from the co-culturing donor cells, in the extracellular matrix and soluble medium from donor cells also increases the levels of arm protein demonstrating that wg can act as a soluble extra cellular signalling molecule.
Ectopic uniform wg expression causes no change in the distribution of arm RNA, but protein distribution is quite different from that in wild type, being evenly distributed at high levels. nkd2 embryos have same pattern of arm RNA expression as those with uniform wg expression, but different protein distribution, with a high level all over, plus 2 stripes/segment where wg is expressed.
arm may play a role in cell-cell adhesive junctions.
A homolog of the arm plakoglobin in Drosophila may link E-cadherin to the underlying actin cytoskeleton at cell-cell junctions. This complex may also participate in the transmission of developmental information.
The role of arm gene expression in pattern formation in imaginal discs has been examined. Mutations in arm and wg have indistinguishable embryonic consequences: the timing and pattern of wg loss in arm mutants is very similar. Clonal tissue with reduced levels of arm activity will only survive in regions furthest from regions of high levels of wg RNA.
Role of arm in neurogenesis has been studied.
A screen for X-linked genes that affect embryo morphology revealed arm.
Genetic mosaics were used to determine that arm is autonomous at the level of the single cell. arm gene activity is required for embryonic development at least until extended germ band stages.
arm mutants display mirror image duplication of denticle belts.
Embryonic lethal; embryonic segmentation defective by time of germ-band shortening; naked cuticle ordinarily comprising the posterior two thirds of each segment replaced by mirror-image duplication of the anteriorly situated denticle belt; strong alleles delete first denticle row in abdominal segments. May have dorsal hole in cuticle. Embryonic CNS development quasi normal (Patel et al., 1989). Autonomous at the level of single cells as shown by denticulate clones of homozygous cells in the naked cuticle of abdominal segments in arm/+ embryos (Wieschaus and Riggleman, 1987). Clones of homozygous female germ cells arrested at stage 10 of oogenesis (Wieschaus and Noell, 1986). An exception is arm8 for which progeny from homozygous germ-line clones have been recovered (Klingsmith et al., 1989). Cell lethal in imaginal discs; although clones of homozygous cells not observed in adults, their formation seems to engender mirror-image duplications, which are not seen in response to homozygosing other cuticular cell lethals (Wieschaus). Transcript found with minor fluctuations in amount, in all cell types at all stages in development (Riggleman, Wieschaus and Schedl, 1989).
Source for merge of: arm l(1)G0192 l(1)G0234
Source for merge of: arm l(1)G0410
