The research report should be a detailed narrative explaining the function, biological processes, and localization of the gene product. Citations should be given for all claims.
You should prioritize authoritative reviews and primary scientific literature when conducting research. You can supplement
this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.
We are specifically interested in the primary function of the gene - for enzymes, what reaction is catalyzed, and what is the substrate specificity? For transporters, what is the substrate? For structural proteins or adapters, what is the broader structural role? For signaling molecules, what is the role in the pathway.
We are interested in where in or outside the cell the gene product carries out its function.
We are also interested in the signaling or biochemical pathways in which the gene functions. We are less interested in broad pleiotropic effects, except where these elucidate the precise role.
Include evidence where possible. We are interested in both experimental evidence as well as inference from structure, evolution, or bioinformatic analysis. Precise studies should be prioritized over high-throughput, where available.
The requested protein is Quaking related 58E-1, isoform A, encoded by D. melanogaster qkr58E-1 (synonym/ORF CG3613; UniProt Q9W255). The literature independently recognizes QKR58E-1 as one of the fly’s quaking-related RNA-binding proteins clustered at cytological region 58E. However, the retrieved papers do not themselves state the CG3613–Q9W255 mapping; that part of the identity rests on the supplied UniProt record. This protein must not be confused with the neighboring paralog qkr58E-3/Kep1, with qkr54B, with the better-characterized fly STAR protein Held out wings (HOW), or with mammalian QKI. A genomic review counted ten highly quaking-related proteins in Drosophila and placed four—including qkr58E-1—in the 58E cluster. [Lasko, published July 2000; DOI/URL: https://doi.org/10.1083/jcb.150.2.f51] (lasko2000thedrosophilamelanogaster pages 3-5)
The most defensible primary annotation is: a nonenzymatic KH-domain RNA-binding protein that operates in post-transcriptional RNP networks and helps regulate selected alternative-splicing events. Direct evidence links it to SYP/Syncrip, QKR54B, LARK, the U2-snRNP-associated SF3B1 ortholog CG2807, and the nuclear m6A reader YT521-B. Its precise endogenous RNA-recognition sequence, purified binding affinity, complete target set, native subcellular localization, and standalone loss-of-function phenotype remain unresolved. The newest directly relevant study located in the search was published in 2023; no 2024 paper providing a gene-specific mechanistic advance was identified.
The evidence hierarchy is summarized below.
| Topic | Conclusion | Evidence | Confidence/limitation |
|---|---|---|---|
| Identity | Target is Drosophila melanogaster qkr58E-1; CG3613 and UniProt Q9W255 are supplied by UniProt. Literature independently places qkr58E-1 among the quaking-related genes clustered at cytological region 58E. | Database-provided accession mapping plus family-level genomic literature (lasko2000thedrosophilamelanogaster pages 3-5) | High for organism, symbol, and 58E-family membership; the retrieved papers did not independently state the CG3613–Q9W255 mapping. Must not be conflated with qkr58E-3/Kep1, how, QKR54B, or mammalian QKI. |
| KH/BBP-like domain | The supplied annotation identifies BBP-like/KH domains, consistent with an RNA-binding protein. Related STAR proteins use KH and QUA2 regions as an extended RNA-binding interface and QUA1 for dimerization. | Domain/database annotation plus family-level inference; STAR-domain architecture review (ehrmann2010posttranscriptionalregulationby pages 53-55) | Moderate for RNA-binding capability; QUA1/QUA2 architecture and dimerization have not been demonstrated directly for QKR58E-1 in the retrieved evidence. |
| Primary molecular function | QKR58E-1 is best annotated as a nonenzymatic RNA-binding and post-transcriptional regulatory protein, participating in RNP networks and regulating selected splice events. No catalytic reaction is indicated. | Direct gene-specific interaction and perturbation evidence (stoiber2015extensivecrossregulationof pages 5-6, lence2016m6amodulatesneuronal pages 3-4) | Moderate–high for post-transcriptional regulation; the complete endogenous target repertoire and precise molecular mechanism remain unresolved. |
| RNP interactions and RNA targets | QKR58E-1 shows reciprocal RNA-regulatory relationships with SYP and QKR54B, associates with transcripts encoding QKR58E-3 and CG6701, and has protein interactions with LARK and CG2807, the fly SF3B1/SAP155 ortholog. Its targets are enriched for ultracomplex genes (P < 5 × 10⁻¹⁰). | Direct RIP/proteomic network evidence, mainly from tagged proteins in S2R+ cells (stoiber2015extensivecrossregulationof pages 5-6, stoiber2015extensivecrossregulationof pages 9-10, stoiber2015biologicalnetworksdynamics pages 32-35) | Moderate; interaction assays establish association, not necessarily direct binding or functional regulation of every partner. Tagged-cell-culture results may not reproduce all native tissue contexts. |
| m6A/YT521-B and splicing | QKR58E-1 interacts with the nuclear m6A reader YT521-B independently of RNA. RNAi depletion altered fl(2)d splicing and only a subset of six additional m6A-regulated events, unlike the broader effects of Nito depletion. | Direct co-immunoprecipitation and RNAi/splicing assays in S2R+ cells (lence2016m6amodulatesneuronal pages 3-4) | Moderate–high for physical association and selected splicing effects; evidence does not establish QKR58E-1 as an m6A reader, methyltransferase-complex component, or universal effector of m6A-dependent splicing. |
| Caper relationship and neural phenotype | In adult head tissue, qkr58E-1 RNA was enriched among Caper RIP targets and validated by RT-PCR. A qkr58E-1 mutation modified the caper gravitaxis defect in both sexes; overall, 13 candidate genes modified the phenotype and 10 of 13 transheterozygotes climbed more slowly than both controls. | Direct 2023 neural RIP and genetic-modifier evidence (titus2023theidentificationof pages 9-11, titus2023theidentificationof pages 13-15) | Moderate; qkr58E-1 is a Caper RNA target and genetic modifier, but the design did not directly prove non-additivity or define a standalone qkr58E-1 loss-of-function phenotype. |
| Subcellular localization | The native compartment in which QKR58E-1 acts has not been directly established in the retrieved studies. Its association with splicing-related factors and YT521-B supports a possible nuclear role, while broader RNP-network membership does not exclude cytoplasmic functions. | Mechanistic inference, not direct imaging or fractionation (stoiber2015biologicalnetworksdynamics pages 32-35, lence2016m6amodulatesneuronal pages 3-4) | Low for a specific localization. Nuclear localization should be treated as a hypothesis rather than an annotation supported by direct QKR58E-1 localization data. |
| Purified RNA specificity | No QKR58E-1-specific purified-protein affinity, consensus RNA motif, substrate sequence, or binding stoichiometry was found. Related STAR proteins recognize short penta-/hexanucleotide elements through KH–QUA2 interfaces. | Family-level biochemical inference only (ehrmann2010posttranscriptionalregulationby pages 53-55) | Unknown for QKR58E-1; motifs and affinity values measured for GLD-1, HOW, or QKI must not be transferred to this protein without direct testing. |
Table: Evidence-strength matrix separating direct qkr58E-1 findings from domain- or family-level inference. It highlights the supported RNA-regulatory role and the major unresolved questions concerning localization and sequence specificity.
The supplied InterPro/Pfam annotations—BBP-like, KH, type-I KH superfamily, and KH-I/KHDC4-BBP—are consistent with an RNA-binding protein. KH domains are compact RNA-binding modules; thus, the domain assignment agrees with the direct experimental classification of QKR58E-1 as an RBP. The literature’s designation of QKR58E-1 as an hnRNP/QKR-family protein further supports this interpretation. (stoiber2015extensivecrossregulationof pages 5-6)
There is nevertheless an annotation nuance. Classical STAR proteins contain an N-terminal QUA1 dimerization region and an extended KH–QUA2 RNA-binding surface. Across experimentally characterized STAR proteins, this surface recognizes short penta- or hexanucleotide elements. Those architectural and mechanistic statements derive from GLD-1, HOW, QKI, and related proteins—not from purified QKR58E-1—and therefore constitute family-level inference only. [Volk and Artzt, 2010; DOI/URL: https://doi.org/10.1007/978-1-4419-7005-3] (ehrmann2010posttranscriptionalregulationby pages 53-55)
Accordingly, QKR58E-1 should not presently be assigned the RNA motif, affinity, stoichiometry, dimerization behavior, or developmental functions measured for HOW, GLD-1, or mammalian QKI. In particular, values such as the approximately 10-nM affinity and 2:1 protein:RNA stoichiometry reported for GLD-1 are not QKR58E-1 measurements. (ehrmann2010posttranscriptionalregulationby pages 53-55)
QKR58E-1 is not an enzyme, transporter, receptor, or structural scaffold in the conventional sense. No catalytic reaction or transported substrate is known. Instead, it is best understood as an RNA-binding post-transcriptional regulator that joins ribonucleoprotein complexes and influences selected RNA-processing outcomes.
The strongest network-scale evidence comes from affinity purification of Drosophila RBPs in S2R+ cells followed by RNA and protein identification. QKR58E-1 participated in a highly interconnected complex containing SYP and QKR54B. Reciprocal relationships were observed: QKR58E-1 bound Syp RNA, SYP bound qkr58E-1 RNA, and the proteins interacted. Reciprocal RNA associations were also reported between QKR58E-1 and QKR54B. QKR58E-1 associated with transcripts encoding QKR58E-3 and CG6701, illustrating cross-regulation among RBP genes rather than functional equivalence of the paralogs. [Stoiber et al., published August 2015; DOI/URL: https://doi.org/10.1101/gr.182675.114; dataset GEO GSE37756] (stoiber2015extensivecrossregulationof pages 5-6, stoiber2015extensivecrossregulationof pages 9-10)
Additional protein associations included LARK and CG2807, the fly ortholog of human SF3B1/SAP155, an integral U2 snRNP component. A connection to CG16941/SF3A1 was also observed in the interaction network. These associations place QKR58E-1 near spliceosome-associated machinery, although affinity purification cannot by itself establish that every association is direct or that QKR58E-1 is a constitutive spliceosomal component. (stoiber2015biologicalnetworksdynamics pages 32-35)
Its RNA targets were especially enriched for “ultracomplex genes”—genes capable of producing many transcript isoforms—with a hypergeometric P < 5 × 10⁻¹⁰. This supports a role in regulating structurally complex transcriptomes. The broader hnRNP/QKR class preferentially associated with relatively low-expression RNAs: RNAs below 1 RPKM were reported to be 1.7-fold more likely to bind an hnRNP/QKR. The latter statistic is class-level, not uniquely attributable to QKR58E-1. (stoiber2015extensivecrossregulationof pages 5-6, stoiber2015biologicalnetworksdynamics pages 35-36)
A 2016 Nature study provides the clearest perturbational evidence. SILAC proteomics following immunoprecipitation of Myc-tagged YT521-B—the fly nuclear m6A reader—identified 73 proteins enriched more than twofold, including 30 predicted RBPs. RNAi screening identified Hrb27C, QKR58E-1, and Nito as regulators of fl(2)d splicing. When six additional m6A-regulated splice events were tested, QKR58E-1 and Hrb27C affected only subsets, whereas Nito depletion more consistently phenocopied depletion of YT521-B and methyltransferase-complex components. [Lence et al., published online 30 November 2016; DOI/URL: https://doi.org/10.1038/nature20568] (lence2016m6amodulatesneuronal pages 3-4, lence2016m6amodulatesneuronal pages 4-5)
Co-immunoprecipitation showed that QKR58E-1 interacts with YT521-B independently of RNA. This supports a protein-level connection to the m6A-responsive splicing apparatus. It does not establish QKR58E-1 as an m6A reader, an m6A writer-complex component, or a universal mediator of m6A-regulated splicing. Indeed, the same study’s evidence for bona fide methyltransferase-complex membership concerned Nito, not QKR58E-1. (lence2016m6amodulatesneuronal pages 3-4, lence2016m6amodulatesneuronal pages 4-5)
The most appropriate pathway assignment is therefore:
mRNA/RNP assembly → interaction with YT521-B and spliceosome-associated proteins → modulation of a selected subset of alternative-splicing events.
QKR58E-1 may help confer target or complex specificity downstream of, or parallel to, m6A recognition. That mechanistic wording remains a model because no study retrieved here demonstrated QKR58E-1 binding directly to methylated RNA or mapped its occupancy against m6A sites.
The most recent gene-specific evidence located was a 2023 analysis of the conserved splicing factor Caper in adult fly nervous tissue. Caper RIP-seq identified 2,451 FLAG-IP RNA targets, 1,138 Caper-antibody targets, and 910 overlapping targets. qkr58E-1 RNA was among 12 targets whose enrichment in FLAG immunoprecipitates was validated by RT-PCR. Thus, qkr58E-1 mRNA is regulated or physically associated with another neuronal post-transcriptional regulator, but this does not show that QKR58E-1 protein binds Caper directly. [Titus et al., published June 2023; DOI/URL: https://doi.org/10.3389/fnmol.2023.1114857; dataset GEO GSE221381] (titus2023theidentificationof pages 6-7, titus2023theidentificationof pages 13-15)
A genetic modifier screen found that a qkr58E-1 mutation modified the caper gravitaxis phenotype in both males and females. Across the screen, 13 candidate genes modified the phenotype, and transheterozygotes for 10 of 13 showed slower climbing than both heterozygous controls. For qkr58E-1, the statistically supported result was an overall genotype effect without a genotype-by-sex interaction. Importantly, the authors stated that their design did not directly establish non-additivity; this is therefore evidence for a genetic modifier relationship, not proof of a direct biochemical interaction or a standalone qkr58E-1 behavioral function. (titus2023theidentificationof pages 9-11)
Collectively, these results connect qkr58E-1 to neuronal RNA regulation and locomotor/gravity-response circuitry, but the evidence remains indirect. No precise qkr58E-1 null analysis, rescue experiment, cell-type-specific knockdown, neuroanatomical defect, or electrophysiological phenotype was found in the retrieved literature.
A definitive native localization cannot be assigned. No retrieved study reported endogenous QKR58E-1 immunofluorescence, tagged-protein localization at physiological expression, or nuclear/cytoplasmic fractionation.
A nuclear role is plausible because QKR58E-1 interacts with nuclear YT521-B, affects alternative splicing, and associates with SF3B1/SF3A1-related machinery. However, its broader association with hnRNP/RNP regulatory networks leaves open cytoplasmic functions in RNA transport, stability, or translation. These possibilities should remain hypotheses rather than database-quality localization annotations. (stoiber2015biologicalnetworksdynamics pages 32-35, lence2016m6amodulatesneuronal pages 3-4)
The safest current cellular-component description is therefore RNA-containing ribonucleoprotein complexes; precise compartment unresolved.
There is no evidence that qkr58E-1 has a clinical, diagnostic, agricultural, or biotechnology implementation. Its current value is as a research target for understanding:
The 2015 interaction dataset (GEO GSE37756) and 2023 Caper dataset (GEO GSE221381) are practical community resources for prioritizing candidate QKR58E-1 targets and interaction partners. (stoiber2015extensivecrossregulationof pages 9-10, titus2023theidentificationof pages 13-15)
KH-domain RNA-binding protein involved in post-transcriptional regulation, including modulation of selected alternative-splicing events through RNP complexes associated with YT521-B and spliceosome-related factors.
The decisive experiments still needed are endogenous-tag localization, purified-protein RNA-binding selection or CLIP-seq, direct comparison of methylated versus unmethylated RNA binding, isoform-resolved knockout and rescue, and tissue-specific perturbation in neurons. Until such evidence is available, motifs and functions established for HOW, qkr58E-3/Kep1, GLD-1, or mammalian QKI should not be transferred to QKR58E-1.
Bottom line: literature for this specific protein is limited but not absent. QKR58E-1/Q9W255 is most strongly supported as a KH-domain post-transcriptional regulator acting in interconnected RNP and selective splicing networks. Its localization and biochemical specificity remain uncharacterized, and the 2023 Caper study is the latest direct functional context identified.
References
(lasko2000thedrosophilamelanogaster pages 3-5): Paul Lasko. The drosophila melanogaster genome: translation factors and rna binding proteins. Journal of Cell Biology, 150:51, Jul 2000. URL: https://doi.org/10.1083/jcb.150.2.f51, doi:10.1083/jcb.150.2.f51. This article has 179 citations and is from a highest quality peer-reviewed journal.
(ehrmann2010posttranscriptionalregulationby pages 53-55): T. Volk and K. Artzt. Post-transcriptional regulation by star proteins. ArXiv, Jan 2010. URL: https://doi.org/10.1007/978-1-4419-7005-3, doi:10.1007/978-1-4419-7005-3. This article has 9 citations.
(stoiber2015extensivecrossregulationof pages 5-6): Marcus H. Stoiber, Sara Olson, Gemma E. May, Michael O. Duff, Jan Manent, Robert Obar, K.G. Guruharsha, Peter J. Bickel, Spyros Artavanis-Tsakonas, James B. Brown, Brenton R. Graveley, and Susan E. Celniker. Extensive cross-regulation of post-transcriptional regulatory networks in drosophila. Genome Research, 25:1692-1702, Aug 2015. URL: https://doi.org/10.1101/gr.182675.114, doi:10.1101/gr.182675.114. This article has 39 citations and is from a highest quality peer-reviewed journal.
(lence2016m6amodulatesneuronal pages 3-4): Tina Lence, Junaid Akhtar, Marc Bayer, Katharina Schmid, Laura Spindler, Cheuk Hei Ho, Nastasja Kreim, Miguel A. Andrade-Navarro, Burkhard Poeck, Mark Helm, and Jean-Yves Roignant. M6a modulates neuronal functions and sex determination in drosophila. Nature, 540:242-247, Nov 2016. URL: https://doi.org/10.1038/nature20568, doi:10.1038/nature20568. This article has 665 citations and is from a highest quality peer-reviewed journal.
(stoiber2015extensivecrossregulationof pages 9-10): Marcus H. Stoiber, Sara Olson, Gemma E. May, Michael O. Duff, Jan Manent, Robert Obar, K.G. Guruharsha, Peter J. Bickel, Spyros Artavanis-Tsakonas, James B. Brown, Brenton R. Graveley, and Susan E. Celniker. Extensive cross-regulation of post-transcriptional regulatory networks in drosophila. Genome Research, 25:1692-1702, Aug 2015. URL: https://doi.org/10.1101/gr.182675.114, doi:10.1101/gr.182675.114. This article has 39 citations and is from a highest quality peer-reviewed journal.
(stoiber2015biologicalnetworksdynamics pages 32-35): MH Stoiber. Biological networks: dynamics, mechanisms and responses. Unknown journal, 2015.
(titus2023theidentificationof pages 9-11): M. Brandon Titus, Adeline W. Chang, Niko Popitsch, Christopher C. Ebmeier, Jeremy M. Bono, and Eugenia C. Olesnicky. The identification of protein and rna interactors of the splicing factor caper in the adult drosophila nervous system. Frontiers in Molecular Neuroscience, Jun 2023. URL: https://doi.org/10.3389/fnmol.2023.1114857, doi:10.3389/fnmol.2023.1114857. This article has 6 citations.
(titus2023theidentificationof pages 13-15): M. Brandon Titus, Adeline W. Chang, Niko Popitsch, Christopher C. Ebmeier, Jeremy M. Bono, and Eugenia C. Olesnicky. The identification of protein and rna interactors of the splicing factor caper in the adult drosophila nervous system. Frontiers in Molecular Neuroscience, Jun 2023. URL: https://doi.org/10.3389/fnmol.2023.1114857, doi:10.3389/fnmol.2023.1114857. This article has 6 citations.
(stoiber2015biologicalnetworksdynamics pages 35-36): MH Stoiber. Biological networks: dynamics, mechanisms and responses. Unknown journal, 2015.
(lence2016m6amodulatesneuronal pages 4-5): Tina Lence, Junaid Akhtar, Marc Bayer, Katharina Schmid, Laura Spindler, Cheuk Hei Ho, Nastasja Kreim, Miguel A. Andrade-Navarro, Burkhard Poeck, Mark Helm, and Jean-Yves Roignant. M6a modulates neuronal functions and sex determination in drosophila. Nature, 540:242-247, Nov 2016. URL: https://doi.org/10.1038/nature20568, doi:10.1038/nature20568. This article has 665 citations and is from a highest quality peer-reviewed journal.
(titus2023theidentificationof pages 6-7): M. Brandon Titus, Adeline W. Chang, Niko Popitsch, Christopher C. Ebmeier, Jeremy M. Bono, and Eugenia C. Olesnicky. The identification of protein and rna interactors of the splicing factor caper in the adult drosophila nervous system. Frontiers in Molecular Neuroscience, Jun 2023. URL: https://doi.org/10.3389/fnmol.2023.1114857, doi:10.3389/fnmol.2023.1114857. This article has 6 citations.