drpr (Draper, Q9W0A0) curation notes

No deep-research provider output was available for this review; these notes were
assembled manually from Europe PMC searches (query TITLE:draper AND drosophila,
sorted by citations, 2026-10-26), the UniProt record and cached publications.

Identity and architecture

• Single-pass type I transmembrane receptor (signal peptide 1-16, TM 801-821),
  extracellular EMI domain followed by many atypical EGF/laminin-EGF repeats;
  InterPro IPR042635 MEGF10/SREC1/2-like; sole fly homolog of MEGF10/11/12 and
  ortholog of C. elegans CED-1 PMID:25111228.
• Intracellular domain carries an NPxY motif (CED-6 adaptor) and an ITAM
  (Src42A phosphorylation, Shark recruitment)
  PMID:18432193;
  PMID:23337816.
• Isoforms: Draper-I (B, displayed, activating, ITAM) vs Draper-II (A,
  ITIM-like, inhibitory via the phosphatase Csw)
  PMID:22426252.

Ligands (recognition)

• Phosphatidylserine, directly, via the EMI/NIM N-terminal region
  PMID:23420848.
  PS-coated beads alone trigger Draper microclusters and engulfment in S2 cells
  PMID:30139739.
• PS bridging by the secreted chemokine-like Orion for neuron debris
  PMID:37276397.
• Pretaporter (ER protein relocated to apoptotic cell surface)
  PMID:19927123.
• S. aureus lipoteichoic acid PMID:19890048.

Signalling

• Src42A -> Draper ITAM phosphorylation -> Shark PMID:18432193.
• CED-6 adaptor via NPxY; junctophilin Undertaker / Ca2+ homeostasis
  PMID:18984163.
• TRAF4 binds the intracellular domain -> MSN -> JNK -> dAP-1/STAT92E transcription
  in reactive glia PMID:28165006.
• Positive feedback: JNK/AP-1 and STAT92E up-regulate draper after injury
  PMID:23618811;
  insulin-like signalling also induces draper PMID:27498858.

Biological contexts (all phagocytic or damage-sensing)

1. Embryonic hemocytes/macrophages: apoptotic cell engulfment PMID:15342648.
2. Embryonic glia: apoptotic neuron clearance downstream of SIMU; in drpr mutants
   corpses are engulfed but accumulate undegraded inside glia
   PMID:18455990.
3. Glia, metamorphosis: mushroom body axon pruning debris
   [PMID:16772168, PMID:16772170].
4. Adult glia (ensheathing/cortex): Wallerian degeneration debris after axotomy
   [PMID:16772169, PMID:19369546, PMID:22426252].
5. NMJ: glia and muscle clear shed presynaptic debris and ghost boutons;
   drpr mutants have reduced synaptic growth PMID:19707574.
6. Epidermal cells engulf degenerating dendrites PMID:24412417.
7. Ovarian follicle cells engulf dying germline (nurse) cells; Draper -> JNK
   PMID:22992958; Draper on phagocytic cup and nascent phagosomes
   PMID:27347682.
8. Salivary gland: cell-autonomous requirement for autophagy during cell death
   PMID:20577216.
9. Cell competition: winner cells engulf Minute losers PMID:17574031.
10. Hemocyte bacterial phagocytosis and defense against S. aureus PMID:19890048.
11. Damage receptor in macrophages: H2O2 -> Src42A -> Draper -> Shark for wound
    recruitment PMID:26028435; corpse engulfment primes macrophages via
    Ca2+/JNK -> raised Draper PMID:27212238; Pez interacts genetically PMID:33296680.
12. Muscle: drpr knockdown in muscle causes degeneration and locomotor defects
    (MEGF10 myopathy model) PMID:25111228.

Curation decisions of note

• Core MF: scavenger receptor activity (IBA, PAINT node seeded by drpr, CED-1,
  MEGF10) plus phosphatidylserine binding; signalling via transmembrane
  signaling receptor activity (ITAM/NPxY). Protein binding rows (Shark, Ced-6,
  Pretaporter) were MODIFIED to transmembrane signaling receptor activity.
• phagocytosis rows modified to the more specific terms already in the gene's
  set: engulfment of apoptotic cell / phagocytosis, engulfment.
• PMID:22992958 is cited by UniProt for "Postsynaptic cell membrane"; the full text
  (follicle cell engulfment) contains no synapse/NMJ data. Recorded as a probable
  WRONG_REFERENCE source defect for UniProt (the claim itself is supported by PMID:19707574).
• Axon location (UniProt, from PMID:16772169) left UNDECIDED: the abstract
  describes Draper as a glial receptor recruited toward severed axons; the full
  text was not accessible to check whether neuronal Draper was shown.
• Wing D/V pattern (IGI, Bx1 suppressor screen): the paper itself states draper
  is not essential for wing development, so over-annotation.
• Organelle-root policy not triggered (no root organelle terms).

Additional literature noted but not used for annotation

• PMID:29109235 glial Draper rescues Abeta toxicity; PMID:28825401 Draper/MMP-1;
  PMID:27647497 aging reduces PI3K/Draper; PMID:32142708 sleep regulates Draper;
  PMID:29520845 Draper-JNK in glial clearance of apoptotic neurons during metamorphosis;
  PMID:36177600 Draper-induced non-autonomous death needs JNK and Src; PMID:42082485
  Notch as a Draper ligand in spermatogonia (2026, not reviewed).