CG6830 (also catalogued as Dro24-1) encodes an 891-residue member of the insect ecdysteroid kinase-like (EcKL) family. The protein carries two CHK kinase-like (APH-type) domains, each of which retains the HxDxxxxN catalytic-loop motif typical of small-molecule kinases of this fold, preceded by a short disordered N-terminal region. EcKL proteins are predicted to be cytosolic kinases that transfer phosphate from ATP to hydroxyl groups on small molecules such as ecdysteroids or dietary and environmental toxins; CG6830 belongs to an expanded dipteran lineage that has been proposed as a candidate for detoxification functions. No substrate, enzymatic activity, subcellular location, endogenous requirement or pathway has been established for CG6830. Ubiquitous misexpression of a CG6830 open reading frame arrests development before the adult stage, a gain-of-function effect whose molecular basis is unknown. The two biochemically characterized ecdysteroid 22-kinases of the family (silkworm BmEc22K and mosquito AgEcK2) lie in other subfamilies.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0106389 ecdysteroid 22-kinase activity | TAS PMID:32540344 Genomic and transcriptomic analyses in Drosophila suggest th... | UNDECIDED | Summary: FlyBase TAS for ecdysteroid 22-kinase activity, traced to the 2020 Drosophila EcKL family analysis. The accessible abstract frames the family as candidate detoxification kinases and reports no CG6830 assay; the full text is not in our cache. CG6830 is not in the PANTHER subfamily of either characterized ecdysteroid 22-kinase, and no PAINT node propagates this activity to its subfamily. Reason: The supporting publication is abstract-only here, so the specific author statement the FlyBase curator relied on cannot be read; per the curation rules this TAS is left UNDECIDED rather than removed. The evidence available leans against a confident transfer of this precise activity. (1) The cited abstract proposes a family-wide detoxification-kinase hypothesis, not a demonstrated ecdysteroid C-22 phosphorylation by CG6830. (2) The 2024 phylogenomic study shows that the only two genes known to encode ecdysteroid kinases (BmEc22K, subfamily A; AgEcK2, subfamily D) lie in different EcKL subfamilies, and treats the expanded subfamily-H dipteran clades, which include the Dro24 lineage, as candidates for detoxification. (3) In PANTHER, CG6830 is in PTHR11012:SF6 together only with the equally uncharacterized CG31099, while BmEc22K is in SF54 and CG5644, the fly ortholog of AgEcK2, is in SF47. (4) The only direct CG6830 experiment, a misexpression screen, gave developmental arrest but did not measure ecdysteroid levels or any enzyme activity. Both CHK domains retain the HxDxxxxN catalytic loop, so a small-molecule kinase activity is plausible, but neither the steroid substrate class nor the C-22 regiospecificity is supported by evolutionary placement or by a target-specific experiment. Supporting Evidence: PMID:32540344 We propose the hypothesis that members of the arthropod-specific ecdysteroid kinase-like (EcKL) gene family encode detoxicative kinases. PMID:38291829 Our results show the only two genes known to encode ecdysteroid kinases belong to different subfamilies and therefore ecdysteroid metabolism functions must be spread throughout the EcKL family. PMID:38291829 Dip1, Dip3, and Dip4 EcKLs in other dipterans should be investigated for possible detoxification functions PMID:39208453 Only misexpression of CG6830 and CG5644 caused significant developmental arrest before the adult stage file:DROME/CG6830/CG6830-bioinformatics/RESULTS-rereview.md both SMART CHK kinase-like domains (174-369 and 605-797) retain file:DROME/CG6830/CG6830-uniprot.txt /note="CHK kinase-like" |
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Download this section (compressed HTML)Q: Does the full text of PMID:32540344 contain a CG6830-specific statement that FlyBase used for the ecdysteroid 22-kinase TAS, or was the annotation applied to the whole EcKL gene group by analogy to BmEc22K?
Q: Are both CHK kinase-like domains of CG6830 catalytically active, and do they act on the same or different substrates?
Experiment: Express recombinant full-length CG6830 and each CHK domain separately, and screen ATP-dependent phosphorylation of ecdysone, 20-hydroxyecdysone and a panel of hydroxylated xenobiotics by LC-MS product identification, with catalytic-loop mutants (D299A, D727A) as controls.
Type: in vitro enzyme assay
Experiment: Repeat the ubiquitous misexpression with catalytic-loop mutant constructs to test whether the developmental arrest depends on phosphotransfer, and generate a CRISPR null allele to test endogenous requirement and xenobiotic sensitivity.
Type: genetic gain and loss of function
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