rpr encodes Reaper, a short Drosophila IAP antagonist that promotes apoptotic caspase activation by binding DIAP1 through an N-terminal IAP-binding motif, inhibiting DIAP1 survival functions, and stimulating UbcD1-dependent DIAP1 autoubiquitination and degradation. A GH3 helical region mediates phospholipid-dependent mitochondrial outer-membrane association and multimerization with Reaper/Hid/Grim family partners, increasing the efficiency of IAP turnover in developmental, steroid-triggered, and DNA-damage-induced apoptosis contexts.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0005515 protein binding | IPI PMID:10675328 Induction of apoptosis by Drosophila reaper, hid and grim th... | MODIFY | Summary: Reaper binds the DIAP1 ubiquitin ligase as part of its pro-apoptotic IAP-antagonist mechanism. Reason: PMID:10675328 shows that reduced Reaper-DIAP1 binding tracks with DIAP1 gain-of-function suppression, so the real interaction should be captured as ubiquitin protein ligase binding rather than generic protein binding. Proposed replacements: ubiquitin protein ligase binding Supporting Evidence: PMID:10675328 REAPER, HID and GRIM kill by forming a complex with DIAP1 |
| GO:0005515 protein binding | IPI PMID:11818065 The damage-responsive Drosophila gene sickle encodes a novel... | UNDECIDED | Summary: The cached Sickle abstract does not verify a Reaper-DIAP1 interaction assay. Reason: The PMID:11818065 abstract directly reports Sickle binding to DIAP1 BIR2 and only discusses Reaper as a related IAP antagonist; full text may include Reaper controls, but the local cache is insufficient to judge this IPI row. Supporting Evidence: PMID:11818065 the N terminus of this protein specifically bound to the BIR2 domain of DIAP1 |
| GO:0005515 protein binding | IPI PMID:12021769 Regulation of Drosophila IAP1 degradation and apoptosis by r... | MODIFY | Summary: Reaper binds DIAP1 while stimulating its UbcD1-dependent autoubiquitination. Reason: Ryoo et al. show direct Reaper-DIAP1 binding in the biochemical pathway that stimulates DIAP1 autoubiquitination, so ubiquitin protein ligase binding is the informative replacement for generic protein binding. Proposed replacements: ubiquitin protein ligase binding Supporting Evidence: PMID:12021769 UBCD1 and Rpr specifically bind to DIAP1 and stimulate DIAP1 auto-ubiquitination in vitro |
| GO:0005515 protein binding | IPI PMID:12021771 The DIAP1 RING finger mediates ubiquitination of Dronc and i... | MODIFY | Summary: Reaper binding to DIAP1 is preserved when the DIAP1 RING is disrupted. Reason: The DIAP1 RING study verifies the Reaper-DIAP1 contact and shows that the RING domain is required for Dronc ubiquitination rather than for Reaper binding; GO:0031625 is a more specific binding term for the DIAP1 E3 interaction. Proposed replacements: ubiquitin protein ligase binding Supporting Evidence: PMID:12021771 Disruption of the DIAP1 RING finger does not inhibit its binding to Rpr, Hid or Dronc |
| GO:0005515 protein binding | IPI PMID:18166655 DIAP2 functions as a mechanism-based regulator of drICE that... | UNDECIDED | Summary: The cached DIAP2 paper verifies Reaper binding to DIAP2 but not this Reaper-DIAP1 row. Reason: PMID:18166655 exposes Rpr binding to DIAP2 BIR2 in the local full text; it may also have a DIAP1 comparator in the full paper or figures, but the cached text does not support this DIAP1 IPI assertion. Supporting Evidence: PMID:18166655 Rpr and Grim preferentially bound to the BIR2 domain of DIAP2 |
| GO:0005515 protein binding | IPI PMID:18166655 DIAP2 functions as a mechanism-based regulator of drICE that... | MODIFY | Summary: Reaper binds DIAP2, a secondary IAP-family ubiquitin ligase. Reason: The DIAP2 BIR2 interaction is real, and because DIAP2 is a RING-containing IAP-family ubiquitin ligase, GO:0031625 is a better replacement than generic protein binding. DIAP1 remains Reaper's genetically dominant IAP target in canonical fly apoptosis. Proposed replacements: ubiquitin protein ligase binding Supporting Evidence: PMID:18166655 Rpr and Grim preferentially bound to the BIR2 domain of DIAP2 |
| GO:0005543 phospholipid binding | IDA PMID:17998202 Mitochondrial localization of Reaper to promote inhibitors o... | ACCEPT | Summary: Reaper binds phospholipids through its GH3 helical domain. Reason: Freel et al. directly assign the GH3 domain to lipid binding that concentrates Reaper on the mitochondrial outer surface and enables efficient DIAP1 degradation. Supporting Evidence: PMID:17998202 Collectively, these data provide a specific function for the GH3 domain in conferring protein-lipid interactions |
| GO:0005739 mitochondrion | IDA PMID:12917412 A GH3-like domain in reaper is required for mitochondrial lo... | ACCEPT | Summary: Reaper localizes to mitochondria through its GH3 region. Reason: The mitochondrion row is correct and reflects a core GH3-dependent membrane-recruitment mechanism that was later refined to phospholipid-mediated localization at the mitochondrial outer surface. Supporting Evidence: PMID:12917412 a small region of Reaper, similar to the GH3 domain of Grim, that is required for localization of Reaper to mitochondria |
| GO:0005741 mitochondrial outer membrane | IDA PMID:17998202 Mitochondrial localization of Reaper to promote inhibitors o... | ACCEPT | Summary: Reaper concentrates on the mitochondrial outer surface. Reason: GH3-lipid interactions place Reaper at the outer surface of mitochondria, positioning Reaper-IAP complexes at membranes for DIAP1 turnover. Supporting Evidence: PMID:17998202 Reaper concentrates on the outer surface of mitochondria |
| GO:0006915 apoptotic process | IDA PMID:11818065 The damage-responsive Drosophila gene sickle encodes a novel... | UNDECIDED | Summary: The cached Sickle abstract does not verify this Reaper apoptotic-process row. Reason: The abstract supports Sickle as a Reaper-region IAP antagonist and only cites Reaper as a known activator of apoptosis; without full-text access, the specific IDA evidence for Reaper should remain unresolved. Supporting Evidence: PMID:11818065 other activators of apoptosis mapping in the Reaper region |
| GO:0006915 apoptotic process | IDA PMID:9294184 Inhibition of reaper-induced apoptosis by interaction with i... | MODIFY | Summary: Reaper-induced apoptosis is better represented as apoptotic signaling. Reason: The older Drosophila IAP study shows that IAPs bind Reaper and block the death program it induces; mechanistically, Reaper acts upstream by antagonizing IAPs, so apoptotic signaling pathway is more precise than top-level apoptotic process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:9294184 The physical interaction of IAPs with RPR provides a molecular mechanism for IAP inhibition of RPR’s apoptotic activity |
| GO:0006915 apoptotic process | IEP PMID:8948586 Activation of the reaper gene during ectopic cell killing in... | MODIFY | Summary: Reaper expression and ectopic killing support a Reaper apoptotic-signaling role. Reason: Nordstrom et al. show that diverse cell-killing stimuli activate rpr and that conditional Reaper expression is sufficient to induce p35-blockable apoptosis, placing Reaper in apoptotic signaling rather than merely at the top-level process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:8948586 conditional expression of REAPER is sufficient to induce massive apoptosis |
| GO:0006915 apoptotic process | IMP PMID:11880355 reaper is required for neuroblast apoptosis during Drosophil... | MODIFY | Summary: Reaper directly contributes to developmental apoptotic signaling in the nervous system. Reason: rpr null animals specifically retain larval neurons and neuroblasts, consistent with Reaper acting through the canonical IAP-antagonist signaling mechanism; GO:0097190 is more informative than a broad apoptotic-process row. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:11880355 central nervous systems of rpr null flies were very enlarged |
| GO:0006915 apoptotic process | IMP PMID:16887178 Drosophila IKK-related kinase regulates nonapoptotic functio... | UNDECIDED | Summary: The DmIKKepsilon abstract does not verify a Reaper apoptosis experiment. Reason: The cached abstract centers on DmIKKepsilon-driven DIAP1 degradation in a nonapoptotic caspase context and does not mention a Reaper perturbation, so this IMP row needs full-text confirmation. Supporting Evidence: PMID:16887178 Drosophila IKK-related kinase (DmIKKvarepsilon) as a regulator of caspase activation in a nonapoptotic context |
| GO:0006915 apoptotic process | IMP PMID:17998202 Mitochondrial localization of Reaper to promote inhibitors o... | MODIFY | Summary: Reaper promotes apoptosis through GH3-dependent mitochondrial DIAP1 degradation. Reason: The GH3/lipid paper connects Reaper binding and membrane localization to accelerated IAP degradation, a proximal apoptotic-signaling mechanism that is narrower than top-level apoptotic process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:17998202 both Reaper binding and mitochondrial localization are required for accelerated IAP degradation |
| GO:0006915 apoptotic process | IMP PMID:20837774 Drosophila IAP antagonists form multimeric complexes to prom... | MODIFY | Summary: Reaper multimerization promotes apoptotic signaling. Reason: Rpr self-association and forced parallel dimerization increase caspase-dependent cell killing, so the broad apoptotic-process row should be tightened to apoptotic signaling pathway. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:20837774 Rpr is able to self-associate and also binds to Hid and Grim |
| GO:0006915 apoptotic process | IMP PMID:8171319 Genetic control of programmed cell death in Drosophila. | MODIFY | Summary: The founding rpr study supports Reaper as a direct trigger of the apoptotic pathway. Reason: White et al. identified rpr as a gene whose product restores and initiates embryonic apoptosis, so apoptotic signaling pathway better captures this direct IAP-antagonist role than the broad parent process. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:8171319 ability of cloned DNA to restore apoptosis to cell death defective embryos |
| GO:0006915 apoptotic process | IMP PMID:8948586 Activation of the reaper gene during ectopic cell killing in... | MODIFY | Summary: Ectopic Reaper expression induces p35-sensitive apoptotic signaling. Reason: The row is mechanistically sound but should use apoptotic signaling pathway because Reaper activates a caspase-mediated death program rather than executing downstream dismantling steps. Proposed replacements: apoptotic signaling pathway Supporting Evidence: PMID:8948586 common apoptotic pathway involving ICE-like protease activity |
| GO:0008630 intrinsic apoptotic signaling pathway in response to DNA damage | IMP PMID:18688282 E2F and p53 induce apoptosis independently during Drosophila... | KEEP AS NON CORE | Summary: Reaper contributes to an RBF/E2F- and p53-dependent DNA-damage apoptosis branch. Reason: Moon et al. show that rpr becomes functionally important in irradiated rbf1 mutant eye discs. This is valid but stress- and tissue-contextual relative to the core DIAP1-antagonist activity. Supporting Evidence: PMID:18688282 the level of cell death seen in rbf1120a discs was clearly reduced when reaper was mutated |
| GO:0012501 programmed cell death | IMP PMID:16168982 Genetic dissection of trophic interactions in the larval opt... | UNDECIDED | Summary: The optic-neuropil abstract does not verify Reaper-specific programmed cell death. Reason: The cached abstract describes larval optic nerve trophic interactions and does not mention rpr or a Reaper perturbation, so the row cannot be assessed from the local source. Supporting Evidence: PMID:16168982 The experiments described here aimed at determining whether Rh5- or Rh6-expressing fibers, as well as the LNv, influence the development of this serotonergic arborization |
| GO:0031398 positive regulation of protein ubiquitination | IDA PMID:12021769 Regulation of Drosophila IAP1 degradation and apoptosis by r... | ACCEPT | Summary: Reaper stimulates DIAP1 protein ubiquitination. Reason: Rpr specifically binds DIAP1 and UbcD1 and stimulates DIAP1 autoubiquitination in a reconstructed ubiquitination reaction. Supporting Evidence: PMID:12021769 function of Rpr in stimulating DIAP1 auto-ubiquitination through UBCD1 |
| GO:0031624 ubiquitin conjugating enzyme binding | IPI PMID:21886178 Drosophila BRUCE inhibits apoptosis through non-lysine ubiqu... | REMOVE | Summary: dBruce binds Reaper as a substrate rather than as a Reaper effector. Reason: PMID:21886178 shows that the E2/E3 dBruce physically interacts with and ubiquitinates Reaper to inhibit apoptosis. Reaper is the ubiquitination target in that relationship, so the dBruce interaction should not be retained as a Reaper ubiquitin-conjugating-enzyme-binding function. Supporting Evidence: PMID:21886178 dBruce targets Reaper for ubiquitination through an unconventional mechanism |
| GO:0031625 ubiquitin protein ligase binding | IPI PMID:12021769 Regulation of Drosophila IAP1 degradation and apoptosis by r... | ACCEPT | Summary: Reaper binds the DIAP1 ubiquitin ligase. Reason: This specific binding term captures the DIAP1 contact through which Reaper stimulates UbcD1-dependent DIAP1 autoubiquitination. Supporting Evidence: PMID:12021769 UBCD1 and Rpr specifically bind to DIAP1 and stimulate DIAP1 auto-ubiquitination in vitro |
| GO:0031625 ubiquitin protein ligase binding | IPI PMID:9294184 Inhibition of reaper-induced apoptosis by interaction with i... | KEEP AS NON CORE | Summary: Reaper binds DIAP2, a secondary IAP-family ubiquitin ligase. Reason: The older IAP coexpression paper verifies Reaper-DIAP2 binding, but DIAP1 is the genetically essential IAP antagonist target in canonical fly apoptosis. Supporting Evidence: PMID:9294184 both baculovirus and Drosophila IAPs physically interact with RPR |
| GO:0035075 response to ecdysone | IMP PMID:10882130 A steroid-triggered transcriptional hierarchy controls saliv... | KEEP AS NON CORE | Summary: rpr is transcriptionally induced downstream of the ecdysone receptor. Reason: Ecdysone directly induces rpr expression before larval salivary-gland death. This is a true tissue-remodeling input to rpr, but the core gene-product activity remains DIAP1 antagonism rather than ecdysone reception. Supporting Evidence: PMID:10882130 rpr is induced directly by the ecdysone-receptor complex through an essential response element in the rpr promoter |
| GO:0035096 larval midgut cell programmed cell death | IGI PMID:15150408 A balance between the diap1 death inhibitor and reaper and h... | KEEP AS NON CORE | Summary: Reaper redundantly promotes larval midgut programmed cell death with Hid. Reason: The midgut row is supported by rpr/hid genetic interaction during steroid-triggered larval tissue destruction, but it is a developmental deployment of the core IAP-antagonist module. Supporting Evidence: PMID:15150408 rpr and hid acting in a redundant manner in the midguts |
| GO:0035193 larval central nervous system remodeling | TAS PMID:10821983 Metamorphosis in drosophila and other insects: the fate of n... | UNDECIDED | Summary: The insect-metamorphosis review abstract does not verify a larval CNS remodeling role for Reaper. Reason: PMID:10821983 is a broad review of neuronal fate during insect metamorphosis and the local abstract does not mention rpr, so this TAS row needs source text that is not present in the cache. Supporting Evidence: PMID:10821983 Other sections deal with the programmed death of motor neurons and its causes, as well as with the metamorphic interactions between motor neurons and their target muscles |
| GO:0042176 regulation of protein catabolic process | IDA PMID:17998202 Mitochondrial localization of Reaper to promote inhibitors o... | MODIFY | Summary: Reaper promotes DIAP1 turnover at membrane surfaces. Reason: The GH3/lipid paper specifically supports positive regulation of DIAP1 degradation, so the narrow ubiquitin-dependent catabolic-process term is more informative than generic regulation of protein catabolism. Proposed replacements: positive regulation of ubiquitin-dependent protein catabolic process Supporting Evidence: PMID:17998202 Reaper can bring the Drosophila IAP (DIAP1) to mitochondria, concomitantly promoting IAP auto-ubiquitination and destruction |
| GO:0042803 protein homodimerization activity | IDA PMID:20837774 Drosophila IAP antagonists form multimeric complexes to prom... | KEEP AS NON CORE | Summary: Reaper self-association supports multimeric IAP-antagonist complexes. Reason: Self-association is a real physical property required for efficient Reaper killing in vivo, but it is best treated as a supporting molecular feature of IAP antagonism. Supporting Evidence: PMID:20837774 Rpr is able to self-associate and also binds to Hid and Grim |
| GO:0043065 positive regulation of apoptotic process | IDA PMID:15107838 Molecular mechanisms of DrICE inhibition by DIAP1 and remova... | ACCEPT | Summary: Reaper positively regulates apoptosis by relieving DIAP1 inhibition of DrICE. Reason: Structural work shows that Reaper, Hid, and Grim use N-terminal motifs to displace DrICE from DIAP1 BIR1, directly explaining how Reaper promotes the apoptotic caspase cascade. Supporting Evidence: PMID:15107838 RHG proteins use their N-terminal IAP-binding motifs to bind to the same surface groove, hence relieving DIAP1-mediated inhibition of DrICE |
| GO:0043065 positive regulation of apoptotic process | IDA PMID:17557079 Drosophila Omi, a mitochondrial-localized IAP antagonist and... | UNDECIDED | Summary: The cached dOmi paper does not verify a Reaper apoptosis assay. Reason: PMID:17557079 establishes dOmi as a mitochondrial IAP antagonist and serine protease; Reaper may have been used as a comparator, but the abstract does not expose an experiment annotatable to rpr. Supporting Evidence: PMID:17557079 Drosophila Omi (dOmi), a fly homologue of the serine protease Omi/HtrA2, is a developmentally regulated mitochondrial intermembrane space protein |
| GO:0046330 positive regulation of JNK cascade | IDA PMID:12198495 Reaper-mediated inhibition of DIAP1-induced DTRAF1 degradati... | KEEP AS NON CORE | Summary: Reaper activates a DIAP1-DTRAF1-JNK side branch. Reason: Reaper relieves DIAP1-mediated DTRAF1 degradation and thereby promotes JNK activation. This is direct but peripheral to the main DIAP1/caspase inhibitory circuit. Supporting Evidence: PMID:12198495 Reaper modulates the JNK pathway through Drosophila inhibitor-of-apoptosis protein 1 |
| GO:0048102 autophagic cell death | IEP PMID:10882130 A steroid-triggered transcriptional hierarchy controls saliv... | KEEP AS NON CORE | Summary: Ecdysone-induced rpr expression participates in larval salivary-gland death. Reason: rpr induction is a direct ecdysone-receptor output during salivary-gland remodeling, but the row captures a tissue-specific autophagic-death program rather than the core Reaper molecular function. Supporting Evidence: PMID:10882130 The steroid hormone ecdysone signals the stage-specific programmed cell death of the larval salivary glands during Drosophila metamorphosis |
| GO:0048102 autophagic cell death | IGI PMID:15150408 A balance between the diap1 death inhibitor and reaper and h... | KEEP AS NON CORE | Summary: Reaper and Hid act redundantly in larval tissue autophagic death. Reason: Yin and Thummel functionally linked ecdysone-induced rpr/hid expression to destruction of larval midguts and salivary glands, supporting this developmental autophagic-cell-death context as non-core. Supporting Evidence: PMID:15150408 ecdysone-induced expression of the death activator genes reaper (rpr) and head involution defective (hid) is required for destruction of the larval midgut and salivary glands |
| GO:0048803 imaginal disc-derived male genitalia morphogenesis | IMP PMID:21389055 Apoptosis controls the speed of looping morphogenesis in Dro... | MARK AS OVER ANNOTATED | Summary: rpr overexpression in male terminalia is an apoptosis manipulation rather than a morphogenesis function. Reason: The cached abstract shows that apoptosis affects male-terminalia looping speed, but it does not establish endogenous Reaper as a morphogenetic executor; this row likely reflects use of Reaper-driven apoptosis to modulate the outcome. Supporting Evidence: PMID:21389055 apoptosis coordinates the outer ring movement that drives the acceleration of genitalia rotation |
| GO:0051402 neuron apoptotic process | IMP PMID:21558369 Coordinated expression of cell death genes regulates neurobl... | KEEP AS NON CORE | Summary: Reaper participates in coordinated neuroblast apoptosis, but the role is context-specific and partially redundant. Reason: The embryonic neuroblast study shows that grim and reaper act together under shared cis-regulation; this neural-progenitor death branch is valid but tissue-specific. Supporting Evidence: PMID:21558369 In the absence of grim and reaper, many neuroblasts survive the embryonic period of cell death |
| GO:0071479 cellular response to ionizing radiation | IDA PMID:11818065 The damage-responsive Drosophila gene sickle encodes a novel... | UNDECIDED | Summary: The cached Sickle paper does not directly support this Reaper ionizing-radiation row. Reason: The PMID:11818065 abstract shows that genotoxic stimuli induce sickle but does not show a Reaper ionizing-radiation experiment, so the row should wait for full-text confirmation. Supporting Evidence: PMID:11818065 Genotoxic stimuli induced skl expression |
| GO:0071480 cellular response to gamma radiation | IMP PMID:24265704 Drosophila UTX coordinates with p53 to regulate ku80 express... | KEEP AS NON CORE | Summary: rpr expression responds to gamma irradiation in a UTX-independent DNA-damage branch. Reason: The UTX study confirms IR-induced rpr/hid expression and H3K27me3 changes at the rpr promoter; this supports a DNA-damage response branch but not the core IAP-antagonist molecular function. Supporting Evidence: PMID:24265704 Figures 5A and 5B show that independent of UTX, the expression levels of these apoptotic genes were upregulated to the same extent following IR exposure both in cell and Drosophila |
| GO:0097190 apoptotic signaling pathway | IGI PMID:10481910 The Drosophila caspase inhibitor DIAP1 is essential for cell... | ACCEPT | Summary: Reaper genetically antagonizes DIAP1 in apoptotic signaling. Reason: Eliminating DIAP1 derepresses caspase-dependent death independently of rpr, hid, and grim, and the same work supports a model in which Rpr and other RHG proteins promote apoptosis by disrupting productive IAP-caspase complexes. Supporting Evidence: PMID:10481910 RPR, HID, and GRIM promote apoptosis by disrupting productive IAP-caspase interactions |
| GO:0097190 apoptotic signaling pathway | IMP PMID:8628996 Cell killing by the Drosophila gene reaper. | ACCEPT | Summary: Reaper is sufficient to trigger p35-sensitive apoptotic signaling. Reason: Forced rpr expression in living cells rapidly induces a caspase-dependent death program, directly placing Reaper in apoptotic signaling. Supporting Evidence: PMID:8628996 RPR appears to activate a death program mediated by a ced-3/ICE (interleukin-1 converting enzyme)-like protease |
| GO:0097190 apoptotic signaling pathway | IMP PMID:9814703 Ras promotes cell survival in Drosophila by downregulating h... | ACCEPT | Summary: Ras/MAPK survival signaling modulates Reaper-induced apoptosis in the eye. Reason: The Ras/MAPK paper used ectopic rpr and hid apoptosis and found that their activity can be enhanced or suppressed by the pathway, consistent with Reaper acting in apoptotic signaling. Supporting Evidence: PMID:9814703 Decreased activity of this pathway enhances, and increased activity suppresses, apoptosis induced by ectopic expression of the cell death regulators reaper (rpr) and head involution defective (hid) |
| GO:1990948 ubiquitin ligase inhibitor activity | IDA PMID:12198495 Reaper-mediated inhibition of DIAP1-induced DTRAF1 degradati... | ACCEPT | Summary: Reaper inhibits DIAP1 ubiquitin ligase output toward DTRAF1. Reason: The DTRAF1/JNK study directly supports Reaper as an inhibitor of DIAP1-mediated DTRAF1 degradation, matching ubiquitin ligase inhibitor activity. Supporting Evidence: PMID:12198495 Expression of Reaper leads to a loss of DIAP1 inhibition of DTRAF1-mediated JNK activation |
| GO:2000060 positive regulation of ubiquitin-dependent protein catabolic process | IGI PMID:12021769 Regulation of Drosophila IAP1 degradation and apoptosis by r... | ACCEPT | Summary: Reaper promotes UbcD1-dependent ubiquitin-mediated degradation of DIAP1. Reason: Ryoo et al. identify stimulation of DIAP1 autoubiquitination through UbcD1 as a direct Reaper function. Supporting Evidence: PMID:12021769 function of Rpr in stimulating DIAP1 auto-ubiquitination through UBCD1 |
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Download this section (compressed HTML)Q: Which endogenous DIAP1 substrates are selected for Reaper-dependent autoubiquitination versus neddylation or nondegradative ubiquitination during normal developmental apoptosis?
Q: Does DIAP2 binding measurably buffer Reaper in any apoptotic tissue, or is Reaper-DIAP2 binding incidental relative to the genetically dominant Reaper-DIAP1 axis?
Q: How do the GH3 helix, Hid-dependent mitochondrial recruitment, and phospholipid binding combine at endogenous expression levels in salivary-gland, midgut, and neuroblast apoptosis?
Experiment: Generate endogenous rpr alleles that separately disrupt the N-terminal IAP-binding motif, the GH3 lipid/Hid interface, and the self-association residues mapped by Sandu et al.; measure DIAP1 ubiquitination, DIAP1 turnover, DrICE/Dronc activity, and developmental apoptosis in embryos, larval midgut, salivary gland, and neuroblast lineages.
Hypothesis: Reaper requires distinct IBM and GH3 surfaces to couple DIAP1 binding to DIAP1 ubiquitin transfer in vivo.
Type: structure-guided endogenous separation-of-function allele series with ubiquitin-remnant proteomics and live caspase reporters
Experiment: Tag endogenous Reaper, compare wild-type and lysine-deficient Reaper in dBruce catalytic mutants, and quantify Reaper abundance, non-lysine ubiquitin conjugates, and DIAP1 occupancy after developmental and genotoxic induction of apoptosis.
Hypothesis: dBruce restrains Reaper abundance through IBM- and GH3-dependent direct ubiquitination without changing the DIAP1-bound Reaper pool.
Type: endogenous epitope tagging with ubiquitin-site proteomics
reaper (rpr) encodes Reaper, Hid, Grim (RHG) protein. It contributes to the caspase dependent apoptosis by inhibiting the anti-apoptotic protein encoded by Diap1.
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