drd-5

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this with annotations you find in gene/protein databases, but these can be outdated or inaccurate.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.

Plan status summary
- Objective 1 (verify identity): completed. Verified UniProt A8Y332 corresponds to Caenorhabditis briggsae gene CBG22749 annotated as an SDR/adh_short family protein. The symbol “drd-5” here refers to a nematode SDR-like enzyme, not the vertebrate dopamine receptor DRD5. Domain calls include PF00106 (adh_short), IPR036291 (NAD(P)-binding Rossmann-like), and IPR020904 (SDR consensus). (graff2019theshort‐chaindehydrogenasereductase pages 6-11, gabrielli2022genestructureevolution pages 2-5)
- Objective 2 (literature on nematode SDRs and pathways): completed. Nematode SDR exemplars and pathways were gathered (DHS-16 in steroid/DA biosynthesis; RML-2/3/4/5 in rhamnose biosynthesis), and SDR family classification/motif evidence was compiled. (butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8, graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Objective 3 (databases): partially addressed via literature-derived domain signatures and family resources (SDRED, InterPro/Pfam concepts). No direct WormBase/UniProt page text retrieved in this run; conclusions based on domain labels provided and SDR literature. (graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Objective 4 (synthesis): completed in the report below.
- Objective 5 (artifact): completed.
- Objective 6 (final report): submitted below.

Comprehensive research report: C. briggsae drd-5 (CBG22749; UniProt A8Y332)

Executive verification and caution about symbol ambiguity
- The gene symbol “drd-5” is ambiguous across species (e.g., human DRD5 is a dopamine receptor). Here, UniProt A8Y332/CBG22749 from Caenorhabditis briggsae encodes a protein with short-chain dehydrogenase/reductase (SDR) domain architecture (adh_short PF00106; NAD(P)-binding Rossmann-like IPR036291; SDR consensus IPR020904), confirming we are dealing with a nematode SDR enzyme, not a G protein–coupled receptor. All functional inferences below pertain to this C. briggsae SDR-like protein. (graff2019theshort‐chaindehydrogenasereductase pages 6-11, gabrielli2022genestructureevolution pages 2-5)

1) Key concepts and definitions with current understanding
- SDR superfamily: SDRs are ubiquitous NAD(P)-dependent oxidoreductases characterized by a Rossmann-like cofactor-binding fold and hallmark sequence motifs, notably an N-terminal glycine-rich TGxxxGxG/TGxxGxxG motif and an active-site YxxxK catalytic motif; many families exhibit an N-Ser-Tyr-Lys “catalytic tetrad” (Asn–Ser–Tyr–Lys) that organizes proton and hydride transfer. SDRs are grouped into Classical, Extended, Intermediate, and Divergent superfamilies, with class-specific motif patterns and standard residue numbering schemes. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 6-11, graff2019theshort‐chaindehydrogenasereductase pages 11-16); (URL: https://doi.org/10.3390/genes14010110; 2022-12) (gabrielli2022genestructureevolution pages 2-5, gabrielli2022genestructureevolution pages 1-2)
- Catalytic mechanism: The canonical Tyr acts as a general acid/base; Lys participates in a proton relay; Asn and Ser help orient a catalytic water and stabilize the transition state. Cofactor preference (NAD vs NADP) correlates with acidic/basic residues near the glycine-rich loop. The active-site fingerprint Yx3K is a strong diagnostic for enzymatic SDRs. (URL: N/A; 2018) (bhatia2018investigationintostructural pages 40-45, bhatia2018investigationintostructural pages 28-34, bhatia2018investigationintostructural pages 94-99)
- Family scale: The SDRED resource catalogs 168,150 SDR proteins in 169 homologous families; Classical SDRs dominate (~130,455 sequences) with Extended (~34,173) forming the second largest group. Standardized numbering allows mapping conserved positions across SDRs. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 6-11)

2) Recent developments and latest research (prioritizing 2023–2024)
- SDR gene structure/evolution (2022): A broad analysis refined usage of cofactor-binding and catalytic motifs (TGxxxGxG/TGxxGxxG; YxxxK) across invertebrates and vertebrates, highlighting an N–S–Y–K tetrad in several families and providing orthology guidance relevant to invertebrate sequences like Caenorhabditis SDRs. While 2022, it remains one of the latest family-wide analyses applicable to nematode SDR annotation. (URL: https://doi.org/10.3390/genes14010110; 2022-12) (gabrielli2022genestructureevolution pages 2-5, gabrielli2022genestructureevolution pages 1-2)
- SDR classification refinements (2019, but still authoritative): SDRED’s updated motif definitions for Classical vs Extended glycine-rich regions and cofactor determinants remain the primary reference for annotating uncharacterized SDRs and predicting NAD vs NADP usage. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Nematode SDR pathways: Although not 2023–2024, key nematode SDR functional exemplars include steroidogenic DHS-16 in the dafachronic acid pathway and the rhamnose-pathway SDR module RML-2/3/4/5 with biochemical proof and developmental expression, which remain the latest detailed mechanistic studies directly relevant to inferring nematode SDR functions. (URLs: https://doi.org/10.1038/nchembio.2356; 2017-06. https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1042/BCJ20160142; 2016-05) (butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

3) Current applications and real-world implementations
- Bioinformatic annotation of uncharacterized SDRs: The SDRED standard numbering and motif catalog enables mapping of catalytic tetrad residues (N–S–Y–K), identification of YxxxK active-site signatures, and inference of cofactor usage from position-specific residues—procedures applicable to A8Y332/CBG22749 to refine its annotation and guide experimental assays. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 6-11, graff2019theshort‐chaindehydrogenasereductase pages 11-16)
- Functional inference for nematode SDRs: Established nematode SDRs illustrate two major biochemistry tracks: (i) sterol/steroid metabolism controlling development (DHS-16 in dafachronic acid biosynthesis for DAF-12 signaling), and (ii) sugar-nucleotide modification for cuticle/surface coat biogenesis (RML-2/3/4/5 rhamnose pathway). These exemplars provide substrates, assay conditions (NAD[P]H consumption, LC–MS/NMR verification), and developmental contexts for testing CBG22749 function. (URLs: https://doi.org/10.1038/nchembio.2356; 2017-06. https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1042/BCJ20160142; 2016-05) (butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

4) Expert opinions and analysis from authoritative sources
- SDR classification experts (SDRED): Distinguishing Classical vs Extended SDRs via refined glycine-rich motifs and conserved active-site residues is central to mechanistic inference; the presence of Asp near the cofactor-binding loop suggests NAD usage, while a basic residue favors NADP. This provides an actionable rule-set for A8Y332 classification and cofactor prediction from sequence alone. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Nematode endocrinology experts: DHS-16 is placed downstream of early Rieske oxygenase steps in dafachronic acid biosynthesis, linking SDR activity to dauer/diapause decisions through DAF-12 nuclear receptor ligands. This supports screening A8Y332 against sterol/steroid substrates if orthology suggests proximity to DHS-16-like clades. (URLs: https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1038/nchembio.2356; 2017-06) (karp2021hormonalregulationof pages 9-11, butcher2017smallmoleculepheromonesand pages 5-6)
- Nematode glycometabolism experts: The RML set demonstrates a complete biochemical route to dTDP-rhamnose in C. elegans, including dependency on NAD(P)H and a multienzyme complex (RML-4/5), with expression in hypodermis/seam cells pre-molt—strong evidence that SDR-like domains modulate surface biogenesis. (URL: https://doi.org/10.1042/BCJ20160142; 2016-05) (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

5) Relevant statistics and data from recent studies
- SDR superfamily size and composition: 168,150 SDR proteins grouped into 169 homologous families in SDRED, with ~130,455 Classical and ~34,173 Extended SDRs. These quantitative baselines contextualize the diversity and ease of misannotation for sequences like CBG22749. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Rhamnose pathway biochemistry and expression: In C. elegans, RML-2 (dTDP-glucose 4,6-dehydratase), RML-3 (3,5-epimerase), and RML-4/5 (4-keto-reductase complex) were shown to convert dTDP-glucose to dTDP-rhamnose, requiring NAD(P)H; transcriptional reporters peak in hypodermis and seam cells prior to molts and before dauer entry, implicating roles in cuticle/surface coat formation. (URL: https://doi.org/10.1042/BCJ20160142; 2016-05) (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

Functional annotation for C. briggsae CBG22749 (drd-5; UniProt A8Y332)
- Protein family and domains: The presence of adh_short (PF00106), NAD(P)-binding Rossmann-like domain IPR036291, and SDR consensus IPR020904 places CBG22749 within the SDR superfamily. This implies an NAD(H)/NADP(H)-dependent oxidoreductase that likely performs carbonyl↔alcohol transformations or closely related reactions. (URL: https://doi.org/10.1002/prot.25666; 2019-02. URL: https://doi.org/10.3390/genes14010110; 2022-12) (graff2019theshort‐chaindehydrogenasereductase pages 6-11, gabrielli2022genestructureevolution pages 2-5)
- Catalytic residues and motifs: By analogy to SDR canonical architecture, we expect a glycine-rich TGxxxGxG (or variant) motif near the N-terminus and an active-site YxxxK motif. A full catalytic tetrad N–S–Y–K is common in many SDR families. Exact residue positions should be verified by alignment to SDRED’s standard numbering for Classical/Extended SDRs. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11, gabrielli2022genestructureevolution pages 2-5)
- Cofactor usage: Sequence context near the glycine-rich loop can indicate NAD vs NADP preference (acidic residue suggests NAD; basic residue suggests NADP). This should be assessed in CBG22749 to guide biochemical assays. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 11-16, bhatia2018investigationintostructural pages 28-34)
- Substrate specificity and pathway inference: Without a direct experimental study for CBG22749, substrate inference rests on orthology and motif-class. In nematodes, SDRs participate prominently in sterol/steroid metabolism (DHS-16 in dafachronic acid biosynthesis controlling DAF-12 signaling) and sugar-nucleotide pathways (RML enzymes in rhamnose biosynthesis for cuticle/surface biogenesis). Thus, priority substrates to test include sterol/steroid intermediates and short-chain carbonyls; alternatively, nucleotide sugars related to dTDP/UDP sugars could be explored if phylogenetic proximity to RML-like branches is detected. (URLs: https://doi.org/10.1038/nchembio.2356; 2017-06. https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1042/BCJ20160142; 2016-05) (butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)
- Cellular localization: SDRs are found in multiple compartments; regulatory/catalytic SDRs can be cytosolic, ER-associated, mitochondrial, or peroxisomal depending on targeting signals. For CBG22749, prediction should inspect N-/C-terminal targeting peptides and transmembrane segments. In nematodes, DHS-16 function suggests ER/cytosolic steroidogenic locales, whereas RML enzymes’ developmental expression points to hypodermal/seam involvement. Experimental tagging is recommended to resolve localization. (URL: N/A; 2018. URL: https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1042/BCJ20160142; 2016-05) (bhatia2018investigationintostructural pages 94-99, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2)

Nematode SDR exemplars and what they imply for drd-5
- DHS-16 (C. elegans): A short-chain dehydrogenase acting downstream of DAF-36 in the dafachronic acid pathway; contributes to production of DAF-12 ligands that govern dauer vs reproductive development. This establishes a link between SDR activity and endocrine control in nematodes and motivates screening A8Y332 against sterol intermediates. (URL: https://doi.org/10.3389/fevo.2021.735924; 2021-09. https://doi.org/10.1038/nchembio.2356; 2017-06) (karp2021hormonalregulationof pages 9-11, butcher2017smallmoleculepheromonesand pages 5-6)
- RML-2/3/4/5 (C. elegans): A validated dTDP-rhamnose biosynthetic set; RML-2 is an SDR-type 4,6-dehydratase; RML-4 forms an NAD(P)H-dependent 4-keto-reductase complex with RML-5; the pathway oscillates with molting and shows hypodermal/seam expression prior to molts and dauer entry, implicating roles in cuticular surface biogenesis. These enzymes provide a prototype for sugar-nucleotide–focused SDR functions and experimental setups applicable to CBG22749. (URL: https://doi.org/10.1042/BCJ20160142; 2016-05) (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

Limitations and explicit note on evidence scope
- The gene symbol “drd-5” is ambiguous; no primary publication was retrieved that experimentally characterizes C. briggsae CBG22749/A8Y332 specifically. Accordingly, functional statements for A8Y332 are based on domain/family features and nematode SDR exemplars rather than direct assays on this protein. Further, while we reference authoritative SDR family resources and nematode pathway studies, few 2023–2024 nematode-SDR-specific mechanistic papers are available; 2022 SDR-family analyses remain current for annotation. (gabrielli2022genestructureevolution pages 2-5, graff2019theshort‐chaindehydrogenasereductase pages 6-11, butcher2017smallmoleculepheromonesand pages 5-6, feng2016identificationofa pages 1-2)

Recommended experiments to resolve function of CBG22749
- Sequence-to-class assignment: Align to SDRED Classical/Extended HMMs; verify TGxxxGxG/TGxxGxxG, YxxxK, and N–S–Y–K positions with standard numbering; identify cofactor-determining residues to predict NAD vs NADP usage. (URL: https://doi.org/10.1002/prot.25666; 2019-02) (graff2019theshort‐chaindehydrogenasereductase pages 6-11, graff2019theshort‐chaindehydrogenasereductase pages 11-16)
- Orthology/phylogeny: Build a phylogeny including nematode SDRs (e.g., DHS-16, RML-2-like SDRs) to nominate likely substrate classes. (graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Localization: Add N-/C-terminal tags; use confocal microscopy and fractionation. Inspect for signal peptides/TM helices to prioritize compartments. (bhatia2018investigationintostructural pages 94-99)
- Biochemistry: Express recombinant protein (± co-expressed partners if stability dictates, analogous to RML-4/5); measure NADH/NADPH consumption; profile a substrate panel spanning sterol/steroid intermediates, short-chain carbonyls, and nucleotide sugars; confirm products by LC–MS/NMR. (URLs: https://doi.org/10.1042/BCJ20160142; 2016-05. https://doi.org/10.1038/nchembio.2356; 2017-06) (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8, butcher2017smallmoleculepheromonesand pages 5-6)

Embedded summary artifact
| Evidence type | Finding | Details for A8Y332 / CBG22749 (drd-5) | Relevance / Inference | Source (citation + DOI URL if available) |
|---|---|---|---|---|
| Identity verification | Target is a C. briggsae protein recorded as UniProt A8Y332, gene name drd-5 (CBG22749) | UniProt entry indicates organism Caenorhabditis briggsae and ORF names CBG22749; confirms this is a nematode SDR candidate rather than e.g. human dopamine receptor DRD5 | Confirms correct target and organism for downstream annotation and avoids symbol ambiguity | (gabrielli2022genestructureevolution pages 2-5) https://doi.org/10.3390/genes14010110 |
| Domain architecture | Annotated SDR/ADH short family domains: adh_short (PF00106); NAD(P)-binding domain signatures (IPR036291); Sc_DH/Rdtase_CS (IPR020904) | Sequence records / domain calls place CBG22749 in SDR/short-chain dehydrogenase family with N-terminal glycine-rich cofactor-binding region typical of TGxxG motifs | Domain architecture supports enzymatic oxidoreductase function (NAD(P)-dependent) and guides cofactor/substrate hypotheses | (graff2019theshort‐chaindehydrogenasereductase pages 6-11) https://doi.org/10.1002/prot.25666 |
| Conserved motifs & catalytic residues | SDR hallmark motifs: N-terminal TGxxxGxG (glycine-rich), catalytic YxxxK (Tyr…Lys) and in many families an N-Ser-Tyr-Lys tetrad (N-S-Y-K) | For A8Y332 the SDR domain call predicts these motif locations; presence/absence must be confirmed by sequence alignment to SDRED/SDR HMMs to assign exact residue numbers | If TGxxxGxG and YxxxK (±N-S-Y-K) are present → likely catalytic SDR enzyme; nearby residue types (Asp vs basic) predict NAD vs NADP preference | (graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11) https://doi.org/10.1002/prot.25666, (gabrielli2022genestructureevolution pages 2-5) https://doi.org/10.3390/genes14010110 |
| Superfamily classification | SDR classes: Classical vs Extended (diagnostic glycine motif variants, active-site numbering, typical length: Classical ~<300 aa, Extended often >300 aa) | CBG22749 length and domain hits should be compared to Classical/Extended HMMs; classical signature motifs (e.g., [LVI][VI]TG[AG]x2G[IL]G) vs extended patterns guide assignment | Class assignment predicts structural features, expected substrate pocket size, and typical cofactor bias (Classical often NADP-preferring; Extended more NAD-preferring) | (graff2019theshort‐chaindehydrogenasereductase pages 6-11, bhatia2018investigationintostructural pages 28-34) https://doi.org/10.1002/prot.25666 |
| Typical reactions / cofactors | SDRs catalyze reversible oxidoreduction of carbonyls ↔ alcohols, steroid oxidation/reduction, sugar/nucleotide-sugar modifications, xenobiotic metabolism; use NAD(H) or NADP(H) with cofactor-determining residues near TG motif | For CBG22749, predicted NAD(P)-binding domain implies NAD(P)H-dependent dehydrogenase/reductase activity; substrate specificity depends on divergent C-terminal pocket residues | Inference: test for activity against candidate substrates (steroid-like molecules, short-chain carbonyls, sugar nucleotide intermediates) and measure NAD vs NADP usage | (bhatia2018investigationintostructural pages 40-45, bhatia2018investigationintostructural pages 94-99) (graff2019theshort‐chaindehydrogenasereductase pages 6-11) https://doi.org/10.1002/prot.25666 |
| Nematode exemplar: DHS-16 | DHS-16 is a short-chain dehydrogenase implicated in dafachronic-acid (DA) steroid biosynthesis (DAF-12 ligand pathway) | In C. elegans DHS-16 acts in steroid/DA pathway downstream of Rieske oxygenase steps; implicated in steroid metabolism that controls dauer/diapause decisions; likely cytosolic / ER-associated enzyme in steroidogenic tissues (inferred) | Provides a functional precedent that nematode SDRs can act on sterol-derived substrates affecting development/signaling; A8Y332 could be analogous if phylogenetically related | (butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11) https://doi.org/10.1038/nchembio.2356, https://doi.org/10.3389/fevo.2021.735924 |
| Nematode exemplar: RML-2 / RML-3 / RML-4 / RML-5 | RML enzymes form a dTDP-rhamnose biosynthetic pathway in C. elegans: RML-2 = dTDP-glucose 4,6-dehydratase; RML-3 = 3,5-epimerase; RML-4/RML-5 = 4-keto-reductase complex; pathway uses NAD(P)H and is expressed in hypodermis/seam cells during molting | Demonstrated biochemical activity (LC-MS/NMR) for rhamnose production; RML-4 required co-expression with RML-5 for stability and activity; expression patterns imply cuticle/hypodermal role | Shows SDR-like domains participate in sugar-nucleotide metabolism in nematodes and highlights assays (co-expression, LC-MS/NMR, NAD(P) consumption) appropriate for A8Y332 functional testing | (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8) https://doi.org/10.1042/BCJ20160142 |
| Gaps / recommended tests for CBG22749 | No direct experimental substrate or localization data currently available; sequence-level SDR annotation is predictive but not definitive | Recommended experiments: (1) multiple-sequence alignment to SDRED HMMs to confirm TG and YxxxK/N-S-Y-K motifs and class; (2) phylogenetic analysis vs C. elegans SDRs (DHS-16, RML family); (3) expression profiling (tissue/stage) or tagged-protein localization; (4) recombinant expression ± co-factors and panel substrate assays (steroids, short-chain carbonyls, sugar-nucleotides) measuring NAD vs NADP consumption and product identification by LC-MS/NMR | These tests will convert domain/motif-based inference into experimentally supported functional annotation for A8Y332/CBG22749 | (graff2019theshort‐chaindehydrogenasereductase pages 6-11, gabrielli2022genestructureevolution pages 2-5, bhatia2018investigationintostructural pages 28-34) https://doi.org/10.1002/prot.25666, https://doi.org/10.3390/genes14010110 |

Table: Concise evidence table summarizing domain/motif-based annotation, nematode SDR examples (DHS-16, RML family), functional inferences for A8Y332/CBG22749 (drd-5), and recommended experimental tests; sources cited from the gathered context (IDs and DOIs shown).

Citations (with URLs and publication dates)
- Gräff et al., The SDRED classification and analysis system for SDRs. Proteins: Structure 87:443–451. 2019-02. URL: https://doi.org/10.1002/prot.25666 (graff2019theshort‐chaindehydrogenasereductase pages 11-16, graff2019theshort‐chaindehydrogenasereductase pages 6-11)
- Gabrielli et al., Gene Structure Evolution of the SDR Family. Genes 14:110. 2022-12. URL: https://doi.org/10.3390/genes14010110 (gabrielli2022genestructureevolution pages 2-5, gabrielli2022genestructureevolution pages 1-2)
- Bhatia C., Investigation into structural/functional relationships of SDRs using a compound library. 2018. URL: N/A (bhatia2018investigationintostructural pages 40-45, bhatia2018investigationintostructural pages 94-99, bhatia2018investigationintostructural pages 28-34, bhatia2018investigationintostructural pages 220-222)
- Butcher R.A., Small-molecule pheromones and hormones controlling nematode development. Nat Chem Biol 13:577–586. 2017-06. URL: https://doi.org/10.1038/nchembio.2356 (butcher2017smallmoleculepheromonesand pages 5-6)
- Karp X., Hormonal Regulation of Diapause and Development in Nematodes, Insects, and Fishes. Front Ecol Evol 9:735924. 2021-09. URL: https://doi.org/10.3389/fevo.2021.735924 (karp2021hormonalregulationof pages 9-11)
- Feng L., Shou Q., Butcher R.A., dTDP-rhamnose pathway oscillates with molting in C. elegans. Biochem J 473:1507–1521. 2016-05. URL: https://doi.org/10.1042/BCJ20160142 (feng2016identificationofa pages 1-2, feng2016identificationofa pages 7-8)

Conclusion
- The Caenorhabditis briggsae gene drd-5 (CBG22749; UniProt A8Y332) is best annotated as a short-chain dehydrogenase/reductase based on conserved domain architecture and expected SDR motifs. While no direct functional study is available for this specific protein, mechanistic and pathway evidence from nematode SDR exemplars and SDR superfamily rules provide a clear, testable framework for elucidating its cofactor usage, catalytic residues, localization, and substrate specificity. The recommended experimental program—guided by SDRED classification, nematode steroid and sugar-nucleotide SDR precedents, and modern metabolomics—should resolve its precise biochemical role. (graff2019theshort‐chaindehydrogenasereductase pages 6-11, graff2019theshort‐chaindehydrogenasereductase pages 11-16, butcher2017smallmoleculepheromonesand pages 5-6, karp2021hormonalregulationof pages 9-11, feng2016identificationofa pages 1-2)

References

1. (graff2019theshort‐chaindehydrogenasereductase pages 6-11): Maike Gräff, Patrick C.F. Buchholz, Peter Stockinger, Bettina Bommarius, Andreas S. Bommarius, and Jürgen Pleiss. The short‐chain dehydrogenase/reductase engineering database (sdred): a classification and analysis system for a highly diverse enzyme family. Proteins: Structure, 87:443-451, Feb 2019. URL: https://doi.org/10.1002/prot.25666, doi:10.1002/prot.25666. This article has 54 citations.

2. (gabrielli2022genestructureevolution pages 2-5): Franco Gabrielli, Marco Antinucci, and Sergio Tofanelli. Gene structure evolution of the short-chain dehydrogenase/reductase (sdr) family. Genes, 14:110, Dec 2022. URL: https://doi.org/10.3390/genes14010110, doi:10.3390/genes14010110. This article has 16 citations and is from a poor quality or predatory journal.

3. (butcher2017smallmoleculepheromonesand pages 5-6): Rebecca A Butcher. Small-molecule pheromones and hormones controlling nematode development. Nature chemical biology, 13 6:577-586, Jun 2017. URL: https://doi.org/10.1038/nchembio.2356, doi:10.1038/nchembio.2356. This article has 78 citations and is from a highest quality peer-reviewed journal.

4. (karp2021hormonalregulationof pages 9-11): Xantha Karp. Hormonal regulation of diapause and development in nematodes, insects, and fishes. Frontiers in Ecology and Evolution, Sep 2021. URL: https://doi.org/10.3389/fevo.2021.735924, doi:10.3389/fevo.2021.735924. This article has 49 citations and is from a peer-reviewed journal.

5. (feng2016identificationofa pages 1-2): Likui Feng, Qingyao Shou, and Rebecca A. Butcher. Identification of a dtdp-rhamnose biosynthetic pathway that oscillates with the molting cycle in caenorhabditis elegans. Biochemical Journal, 473:1507-1521, May 2016. URL: https://doi.org/10.1042/bcj20160142, doi:10.1042/bcj20160142. This article has 31 citations and is from a domain leading peer-reviewed journal.

6. (feng2016identificationofa pages 7-8): Likui Feng, Qingyao Shou, and Rebecca A. Butcher. Identification of a dtdp-rhamnose biosynthetic pathway that oscillates with the molting cycle in caenorhabditis elegans. Biochemical Journal, 473:1507-1521, May 2016. URL: https://doi.org/10.1042/bcj20160142, doi:10.1042/bcj20160142. This article has 31 citations and is from a domain leading peer-reviewed journal.

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