D7r4 is a short-form salivary protein from female Anopheles gambiae mosquitoes that facilitates blood feeding by binding and sequestering host biogenic amines (serotonin, histamine, norepinephrine, and tryptamine). It functions as a "kratagonist" - capturing host signaling molecules with high affinity to prevent their vasoconstrictive and inflammatory effects. The crystal structure of D7r4 has been solved (PDB: 2PQL, 2QEB, 2QEH, 2QEO, 2QEV) at high resolution (2.0-2.31 Angstroms), revealing a modified OBP-like fold with eight alpha-helices, three disulfide bonds, and a binding pocket adapted to amine ligands. D7r4 is secreted into saliva during blood feeding and belongs to the PBP/GOBP (Pheromone/Odorant-Binding Protein) structural family but has evolved a distinct function unrelated to olfaction.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
|
GO:0005615
extracellular space
|
IBA
GO_REF:0000033 |
ACCEPT |
Summary: This annotation correctly describes D7r4's localization based on phylogenetic inference. D7r4 is a secreted salivary protein with a signal peptide (residues 1-21) that is released into the extracellular space during blood feeding [UniProt Q7PNF2].
Reason: D7r4 is confirmed to be a secreted protein localized to female saliva. UniProt states "SUBCELLULAR LOCATION: Secreted" with evidence from PMID:17913537. The IBA annotation from phylogenetic trees is consistent with the IDA evidence for the same term. The protein contains a signal peptide and is found in the extracellular salivary compartment from which it is injected into the host during blood feeding [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
-!- SUBCELLULAR LOCATION: Secreted
PMID:17913537
A proteomic and immunoproteomic analysis of anopheles and Aedes saliva allowed for the identification of some antigens that were recognized by most of the exposed individuals
|
|
GO:0007608
sensory perception of smell
|
IBA
GO_REF:0000033 |
REMOVE |
Summary: This annotation is INCORRECT. D7r4 is expressed exclusively in female salivary glands and functions in blood feeding, not in olfactory perception. The IBA annotation was inferred from homology to Drosophila odorant-binding proteins, but D7 proteins have evolved a completely different function in mosquito saliva.
Reason: D7r4 is expressed specifically in female salivary glands, not olfactory tissues [PMID:12062411, PMID:11841502]. UniProt explicitly states the tissue specificity. The D7 proteins have evolutionarily repurposed the OBP-like fold from olfactory function to biogenic amine binding in saliva [PMID:16301315]. The IBA annotation appears to be based on structural family membership (PBP/GOBP) shared with Drosophila odorant-binding proteins, but this does not predict function. D7r4 binds serotonin, histamine, and norepinephrine - not odorants [PMID:17928288]. Deep research confirms short-form D7s "predominantly bind biogenic amines" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
-!- TISSUE SPECIFICITY: Female saliva (at protein level) (PubMed:17913537). Female salivary gland (PubMed:12062411). Not detected in female carcass without salivary glands (PubMed:12062411). Not detected in male tissues
PMID:16301315
The D7 salivary family of proteins is abundantly expressed in blood-feeding Diptera and is distantly related to the odorant-binding protein superfamily
|
|
GO:0005549
odorant binding
|
IEA
GO_REF:0000002 |
MODIFY |
Summary: This annotation is based on structural family membership (PBP/GOBP family via InterPro IPR006170) but does not reflect the actual function of D7r4. The protein binds biogenic amines (serotonin, histamine, norepinephrine, tryptamine), not odorants, and has no role in olfaction. Crystal structures with bound ligands demonstrate this directly.
Reason: D7r4 belongs to the PBP/GOBP structural family (InterPro IPR006170), which led to this IEA annotation. However, the D7 proteins have evolutionarily repurposed this fold for binding biogenic amines in saliva, not odorants in antennae. D7r4 is expressed exclusively in female salivary glands [PMID:12062411], not olfactory tissues. The actual molecular functions are serotonin binding (GO:0051378), histamine binding (GO:0051381), norepinephrine binding (GO:0051380), and tryptamine binding. Crystal structures of D7r4 with bound serotonin (PDB:2QEH), histamine (PDB:2QEB), norepinephrine (PDB:2QEO), and tryptamine (PDB:2PQL) demonstrate the actual binding specificity [PMID:17928288]. UniProt documents specific binding residues for each ligand. The GO:0005549 definition "Binding to an odorant, any substance capable of stimulating the sense of smell" does not apply - serotonin, histamine, norepinephrine, and tryptamine are not odorants. Deep research confirms short-form D7s "predominantly bind biogenic amines (serotonin/5-HT, histamine, epinephrine/norepinephrine)" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
Binds serotonin, noradrenaline, histamine and tryptamine
UniProt:Q7PNF2
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito Anopheles gambiae
|
|
GO:0005576
extracellular region
|
IEA
GO_REF:0000044 |
ACCEPT |
Summary: This annotation correctly reflects the subcellular localization of D7r4 as a secreted salivary protein. The IEA annotation from UniProt subcellular location vocabulary is appropriate.
Reason: D7r4 is a secreted protein with a signal peptide (residues 1-21) [UniProt Q7PNF2]. It is released into the extracellular space (saliva) during blood feeding. The UniProt entry confirms "SUBCELLULAR LOCATION: Secreted" with experimental evidence from PMID:17913537. This is an appropriate CC annotation at the broader level. Deep research confirms D7 proteins are "secreted into saliva at the skin interface during probing/feeding" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
-!- SUBCELLULAR LOCATION: Secreted
|
|
GO:0042311
vasodilation
|
IEA
GO_REF:0000043 |
ACCEPT |
Summary: This annotation is technically correct but represents the downstream physiological effect rather than the direct biological process. D7r4 exhibits vasodilating activity by sequestering vasoconstrictors (serotonin, norepinephrine) from the host.
Reason: UniProt confirms D7r4 "Exhibits vasodilating activity" [UniProt Q7PNF2]. The mechanism is indirect - D7r4 sequesters serotonin and norepinephrine, which are vasoconstrictors, thereby preventing vasoconstriction and allowing vasodilation at the bite site. PMID:16301315 states D7 proteins "bind serotonin with high affinity, as well as histamine and norepinephrine" and that "Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties." While the annotation captures a real physiological effect, it is a downstream consequence of the kratagonist mechanism. However, since this is documented in the literature, it should be retained. Deep research confirms biogenic amine scavenging "counteracts platelet aggregation, vasoconstriction, and nociception during feeding" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
Exhibits vasodilating activity (PubMed:16301315)
PMID:16301315
Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties
|
|
GO:0097746
blood vessel diameter maintenance
|
IEA
GO_REF:0000043 |
KEEP AS NON CORE |
Summary: This annotation is a parent term of vasodilation and is somewhat redundant. D7r4 affects blood vessel diameter by counteracting vasoconstriction through sequestration of host biogenic amines.
Reason: This annotation is inferred from the UniProt keyword "Vasodilator" via GO_REF:0000043. While technically accurate as a broader term encompassing vasodilation, it is less informative than GO:0042311 (vasodilation) which is also annotated. The primary mechanism of D7r4 is sequestration of vasoconstrictive amines, with blood vessel diameter maintenance being a downstream physiological consequence. This should be kept as a non-core annotation since it accurately reflects a real biological effect but is not the primary function of the protein.
Supporting Evidence:
UniProt:Q7PNF2
Exhibits vasodilating activity (PubMed:16301315)
|
|
GO:0005615
extracellular space
|
IDA
PMID:17913537 Antibody response against saliva antigens of Anopheles gambi... |
ACCEPT |
Summary: This is high-quality experimental evidence from mass spectrometry identification of D7r4 in female mosquito saliva. This annotation should be accepted as representing the experimentally determined localization.
Reason: PMID:17913537 provides direct experimental evidence (IDA - Inferred from Direct Assay) for D7r4 localization in the extracellular space (saliva). The study performed proteomic analysis of Anopheles gambiae saliva and identified D7r4 by mass spectrometry. UniProt confirms "Female saliva (at protein level) (PubMed:17913537)" [UniProt Q7PNF2]. This experimental evidence strongly supports the CC annotation.
Supporting Evidence:
PMID:17913537
A proteomic and immunoproteomic analysis of anopheles and Aedes saliva allowed for the identification of some antigens that were recognized by most of the exposed individuals
UniProt:Q7PNF2
-!- TISSUE SPECIFICITY: Female saliva (at protein level) (PubMed:17913537)
|
|
GO:0051378
serotonin binding
|
IDA
PMID:17928288 The crystal structure of D7r4, a salivary biogenic amine-bin... |
NEW |
Summary: D7r4 binds serotonin with high affinity as demonstrated by direct binding assays and crystal structure with bound serotonin (PDB:2QEH). This is a core molecular function.
Reason: UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound serotonin (PDB:2QEH) at 2.10 Angstrom resolution demonstrates the binding mode directly [PMID:17928288]. Specific binding residues are documented: Glu-28, His-56, Tyr-115, Asp-132, and Glu-135. Mutagenesis studies confirm these residues are critical for serotonin binding - E28L and E135L mutations significantly reduce serotonin binding [UniProt Q7PNF2]. GO:0051378 definition "Binding to serotonin (5-hydroxytryptamine), a monoamine neurotransmitter" accurately describes this function. PMID:16301315 states "four of these five short D7 proteins and the D7 long form bind serotonin with high affinity".
Supporting Evidence:
UniProt:Q7PNF2
Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
UniProt:Q7PNF2
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito Anopheles gambiae
PMID:16301315
four of these five short D7 proteins and the D7 long form bind serotonin with high affinity, as well as histamine and norepinephrine
|
|
GO:0051381
histamine binding
|
IDA
PMID:17928288 The crystal structure of D7r4, a salivary biogenic amine-bin... |
NEW |
Summary: D7r4 binds histamine with high affinity as demonstrated by direct binding assays and crystal structure with bound histamine (PDB:2QEB). This is a core molecular function.
Reason: UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound histamine (PDB:2QEB) at 2.00 Angstrom resolution demonstrates the binding mode directly [PMID:17928288]. Specific binding residues are documented: Tyr-115, Asp-132, and Glu-135. UniProt states D7r4 "Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle contraction" [UniProt Q7PNF2]. GO:0051381 definition "Binding to histamine, a physiologically active amine" accurately describes this function. PMID:16301315 demonstrates histamine binding activity.
Supporting Evidence:
UniProt:Q7PNF2
Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle contraction (PubMed:16301315)
UniProt:Q7PNF2
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito Anopheles gambiae
|
|
GO:0051380
norepinephrine binding
|
IDA
PMID:17928288 The crystal structure of D7r4, a salivary biogenic amine-bin... |
NEW |
Summary: D7r4 binds norepinephrine as demonstrated by direct binding assays and crystal structure with bound norepinephrine (PDB:2QEO). This is a core molecular function.
Reason: UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound norepinephrine (PDB:2QEO) at 2.31 Angstrom resolution demonstrates the binding mode directly [PMID:17928288]. Specific binding residues are documented: Glu-28, Phe-43, Asp-132, and Glu-135. UniProt states D7r4 "Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle contraction" [UniProt Q7PNF2]. GO:0051380 definition "Binding to norepinephrine" accurately describes this function. PMID:16301315 states D7 short proteins bind "norepinephrine" with high affinity.
Supporting Evidence:
UniProt:Q7PNF2
Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
UniProt:Q7PNF2
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the malaria mosquito Anopheles gambiae
|
|
GO:0035821
modulation of process of another organism
|
IDA
PMID:16301315 Function and evolution of a mosquito salivary protein family |
NEW |
Summary: D7r4 modulates host hemostatic and inflammatory responses during blood feeding by sequestering host biogenic amines. This is an appropriate BP annotation for the cross-species effect.
Reason: D7r4 clearly modulates processes in the vertebrate host. UniProt states "Modulates blood feeding of female mosquitoes on vertebrate species by binding and sequestering different mediators involved in the host response" [UniProt Q7PNF2]. The GO:0035821 definition "A process in which an organism effects a change in a biological process in another organism" accurately captures this function. By sequestering serotonin, histamine, and norepinephrine from the host, D7r4 prevents vasoconstriction, platelet aggregation, and inflammation. PMID:16301315 confirms "Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties." Deep research describes D7 proteins as "kratagonists - high-affinity scavengers of host small-molecule inflammatory and hemostatic mediators" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
UniProt:Q7PNF2
Modulates blood feeding of female mosquitoes on vertebrate species by binding and sequestering different mediators involved in the host response
PMID:16301315
Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties
|
|
GO:1900047
negative regulation of hemostasis
|
IDA
PMID:16301315 Function and evolution of a mosquito salivary protein family |
NEW |
Summary: D7r4 negatively regulates host hemostasis by sequestering biogenic amines that promote platelet aggregation and vasoconstriction. This is a core biological process annotation.
Reason: By sequestering serotonin (which promotes platelet aggregation) and norepinephrine (a vasoconstrictor), D7r4 negatively regulates the host hemostatic response at the bite site. PMID:16301315 states "Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties." GO:1900047 definition "Any process that stops, prevents or reduces the frequency, rate or extent of hemostasis" accurately captures this function. Deep research confirms biogenic amine scavenging "counteracts platelet aggregation, vasoconstriction, and nociception during feeding" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
Supporting Evidence:
PMID:16301315
Scavenging of host amines would antagonize their vasoconstrictor, platelet-aggregating, and pain-inducing properties
|
Q: What are the binding affinities (Kd values) of D7r4 for each of its ligands (serotonin, histamine, norepinephrine, tryptamine), and does it show preference for one over others?
Suggested experts: Andersen JF, Mans BJ, Ribeiro JM
Q: Do the different D7 short forms (D7r1-5) have distinct ligand binding specificities that enable non-redundant function during blood feeding?
Suggested experts: Calvo E, Mans BJ
Q: What is the structural basis for D7r4's ability to bind multiple chemically distinct biogenic amines in the same binding pocket?
Suggested experts: Andersen JF, Mans BJ
Experiment: Generate D7r4 knockout A. gambiae using CRISPR and measure blood meal size, feeding time, feeding success rate, and host inflammatory responses compared to wild-type controls
Hypothesis: D7r4 knockout mosquitoes will have reduced blood feeding efficiency due to enhanced host hemostatic and inflammatory responses
Type: Gene knockout and feeding assay
Experiment: Perform comparative structural analysis and ancestral sequence reconstruction to determine which amino acid changes are responsible for the shift from odorant to biogenic amine binding
Hypothesis: D7r4 has evolved from odorant-binding proteins through changes in ligand binding specificity
Type: Structural biology and molecular evolution
Experiment: Perform competitive binding assays with all D7 short forms (D7r1-5) against a panel of biogenic amines to determine the binding specificity landscape of the D7 short form family
Hypothesis: D7r4 and other D7 short forms have non-overlapping ligand preferences that together provide comprehensive sequestration of host mediators
Type: Binding assays and functional complementation
provider: falcon
model: Edison Scientific Literature
cached: false
start_time: '2026-01-30T08:21:34.418035'
end_time: '2026-01-30T08:26:48.953315'
duration_seconds: 314.54
template_file: templates/gene_research_go_focused.md
template_variables:
organism: ANOGA
gene_id: D7r4
gene_symbol: D7r4
uniprot_accession: Q7PNF2
protein_description: 'RecName: Full=Short form salivary protein D7R4 {ECO:0000305};
AltName: Full=D7-related 4 protein {ECO:0000312|EMBL:AAK84945.1}; AltName: Full=D7r4
protein {ECO:0000312|EMBL:CAC35524.1}; Flags: Precursor;'
gene_info: Name=D7r4 {ECO:0000303|PubMed:16301315}; ORFNames=AgaP_AGAP008281 {ECO:0000312|EMBL:EAA12291.2};
organism_full: Anopheles gambiae (African malaria mosquito).
protein_family: Belongs to the PBP/GOBP family. .
protein_domains: PBP/GOBP. (IPR006170); PBP_GOBP_sf. (IPR036728); PBP_GOBP (PF01395)
provider_config:
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citation_count: 19
BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.
DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'D7r4' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information
Please provide a comprehensive research report on the gene D7r4 (gene ID: D7r4, UniProt: Q7PNF2) in ANOGA.
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.
Question: You are an expert researcher providing comprehensive, well-cited information.
Provide detailed information focusing on:
1. Key concepts and definitions with current understanding
2. Recent developments and latest research (prioritize 2023-2024 sources)
3. Current applications and real-world implementations
4. Expert opinions and analysis from authoritative sources
5. Relevant statistics and data from recent studies
Format as a comprehensive research report with proper citations. Include URLs and publication dates where available.
Always prioritize recent, authoritative sources and provide specific citations for all major claims.
BEFORE YOU BEGIN RESEARCH: You MUST verify you are researching the CORRECT gene/protein. Gene symbols can be ambiguous, especially for less well-characterized genes from non-model organisms.
DO NOT PROCEED WITH RESEARCH ON A DIFFERENT GENE. Instead:
- State clearly: "The gene symbol 'D7r4' is ambiguous or literature is limited for this specific protein"
- Explain what you found (e.g., "Found extensive literature on a different gene with the same symbol in a different organism")
- Describe the protein based ONLY on the UniProt information provided above
- Suggest that the protein function can be inferred from domain/family information
Please provide a comprehensive research report on the gene D7r4 (gene ID: D7r4, UniProt: Q7PNF2) in ANOGA.
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.
Research report: D7r4 (AGAP008281; UniProt Q7PNF2) from Anopheles gambiae
Verification of identity and context
- Gene/protein identity: D7r4 is one of four short-form D7-related salivary proteins (D7r1–r4) encoded in a genomic cluster on chromosome arm 3R in Anopheles gambiae; these proteins are abundantly expressed in adult female salivary glands and secreted during blood feeding (Arcà et al., Insect Molecular Biology, Feb 2002; https://doi.org/10.1046/j.0962-1075.2001.00309.x) (arca2002aclusterof pages 1-2). The protein was structurally and functionally characterized as a biogenic amine–binding D7 short form from A. gambiae (Mans et al., J. Biol. Chem., Dec 2007; online Oct 9, 2007; https://doi.org/10.1074/jbc.M706410200) (mans2007thecrystalstructure pages 1-1, mans2007thecrystalstructure pages 8-9).
- Organism: African malaria mosquito Anopheles gambiae; D7 family members are female-salivary proteins injected into host skin (Arcà 2002; https://doi.org/10.1046/j.0962-1075.2001.00309.x) (arca2002aclusterof pages 1-2). Serological profiling of A. gambiae D7 proteins, including D7r4, confirmed immunogenicity in exposed humans (Oseno et al., Parasites & Vectors, Jan 2022; https://doi.org/10.1186/s13071-021-05130-5) (oseno2022characterizationofanopheles pages 1-2).
- Family/domains: D7 proteins are OBP-like helical proteins related to insect pheromone/odorant-binding proteins (PBP/GOBP); short forms (like D7r4) are single-domain, all-α-helical proteins stabilized by conserved disulfides (Andersen, Toxicon, Dec 2010; https://doi.org/10.1016/j.toxicon.2009.11.002) (andersen2010structureandmechanism pages 8-9).
Key concepts and definitions
- D7 family: Highly expressed salivary proteins of blood-feeding mosquitoes that bind and sequester host small-molecule mediators of hemostasis and inflammation (biogenic amines, eicosanoids), mitigating vasoconstriction, platelet activation, and inflammation at the bite site (Andersen 2010; https://doi.org/10.1016/j.toxicon.2009.11.002) (andersen2010structureandmechanism pages 8-9).
- Short-form D7s: Single-domain OBP-like proteins typified by D7r4 in A. gambiae that bind biogenic amines (Mans et al., J. Biol. Chem. 2007; https://doi.org/10.1074/jbc.M706410200) (mans2007thecrystalstructure pages 1-1, mans2007thecrystalstructure pages 8-9).
Functional annotation of D7r4
- Biochemical function and ligand specificity: Recombinant and crystallographic analyses established that D7r4 binds biogenic amines, including serotonin, norepinephrine, histamine, and tryptamine, consistent with a role in scavenging vasoactive and pro-inflammatory amines during feeding (Mans et al., J. Biol. Chem., Dec 2007; https://doi.org/10.1074/jbc.M706410200) (mans2007thecrystalstructure pages 1-1, mans2007thecrystalstructure pages 8-9). Structural interpretation indicates hydrogen bonding between the protonated amine and acidic residues (e.g., Asp/Glu) and packing of the aromatic ring in a hydrophobic pocket; histamine binds with somewhat lower affinity than serotonin/catecholamines (Andersen, Toxicon, Dec 2010; https://doi.org/10.1016/j.toxicon.2009.11.002) (andersen2010structureandmechanism pages 8-9).
- Mechanistic role in pathways: By sequestering biogenic amines, D7r4 is inferred to dampen vasoconstriction (e.g., norepinephrine), itch/inflammation (e.g., histamine), and platelet activation (e.g., serotonin), thereby facilitating blood meal acquisition at the skin interface (Mans 2007; https://doi.org/10.1074/jbc.M706410200; Andersen 2010; https://doi.org/10.1016/j.toxicon.2009.11.002) (mans2007thecrystalstructure pages 1-1, andersen2010structureandmechanism pages 8-9).
Structure and domain organization
- Structural data: The crystal structure of A. gambiae D7r4 was solved in unliganded and ligand-bound forms, revealing an OBP-like fold comprising approximately eight α-helices with three disulfide bonds. Ligand-bound structures define a pocket accommodating biogenic amines with specific polar contacts and aromatic stacking (Mans et al., J. Biol. Chem., Dec 2007; PDB coordinates referenced therein; https://doi.org/10.1074/jbc.M706410200) (mans2007thecrystalstructure pages 8-9, mans2007thecrystalstructure pages 1-1). Review synthesis corroborates this architecture and ligand-contact network (Andersen 2010; https://doi.org/10.1016/j.toxicon.2009.11.002) (andersen2010structureandmechanism pages 8-9).
Localization and site of action
- Tissue/cellular localization: D7r4 is part of a salivary gland–expressed gene cluster; proteins are secreted into saliva and delivered to host skin during probing/feeding by adult females (Arcà 2002; https://doi.org/10.1046/j.0962-1075.2001.00309.x) (arca2002aclusterof pages 1-2). Human serologic evidence confirms exposure to D7 family antigens, including D7r4, at field sites with different transmission intensities (Oseno 2022; https://doi.org/10.1186/s13071-021-05130-5) (oseno2022characterizationofanopheles pages 1-2).
Quantitative data and statistics
- Binding and kinetics: The primary structural papers characterize D7r4 as high-affinity for several biogenic amines; relative binding preferences indicate stronger binding to serotonin and norepinephrine than to histamine in structural and mutational context (qualitative trend). Exact Kd values are not specified in the excerpts used here and should be taken from the original measurements in Mans et al. 2007 (https://doi.org/10.1074/jbc.M706410200) (mans2007thecrystalstructure pages 1-1, andersen2010structureandmechanism pages 8-9).
- Serology/exposure gradients: In a 2022 cohort study comparing malaria-naive Europeans, moderate-transmission (Junju, Kenya), and high-transmission (Kitgum, Uganda) settings, IgG responses to several A. gambiae D7 antigens, including D7r4, were strongest in the high-transmission area and lowest in malaria-naive individuals, supporting utility of D7 proteins as exposure biomarkers (Oseno 2022; Jan 2022; https://doi.org/10.1186/s13071-021-05130-5) (oseno2022characterizationofanopheles pages 1-2).
Recent developments and latest research (with priority to recent sources)
- Biomarker applications: D7 proteins, including D7r4 among the panel tested, continue to be evaluated as serological markers of vector exposure, with field data indicating exposure-dependent IgG profiles and potential for monitoring intervention impact (Oseno 2022; Parasites & Vectors; Jan 2022; https://doi.org/10.1186/s13071-021-05130-5) (oseno2022characterizationofanopheles pages 1-2).
- Comparative structural/functional insights: Cross-lineage comparisons emphasize conserved OBP-like scaffolds and the diversification of ligand pockets across D7 family members, with short-form proteins in mosquitoes primarily adopting biogenic amine binding, while long forms can target eicosanoids (Jablonka et al., Sci. Rep., Mar 2019; https://doi.org/10.1038/s41598-019-41848-0) (jablonka2019functionalandstructural pages 9-10, jablonka2019functionalandstructural pages 1-2).
- Note on 2023–2024: We found limited D7r4-specific publications in 2023–2024 within the retrieved evidence set; however, the broader D7 family continues to be the subject of structural/functional and sero-epidemiological studies. Key mechanistic and structural conclusions for D7r4 remain anchored in primary structural work and authoritative reviews cited above (mans2007thecrystalstructure pages 1-1, andersen2010structureandmechanism pages 8-9, oseno2022characterizationofanopheles pages 1-2).
Current applications and implementations
- Exposure surveillance: Recombinant D7 salivary proteins, including D7r4, have been deployed in sero-assays to quantify human–vector contact and to evaluate vector control measures; age-related trends and intervention associations (e.g., bednet use) were particularly evident for some D7 antigens (Oseno 2022; https://doi.org/10.1186/s13071-021-05130-5) (oseno2022characterizationofanopheles pages 1-2).
- Therapeutic inspiration: Reviews and comparative analyses highlight D7 scaffolds as sources of anti-inflammatory/anti-hemostatic mechanisms (e.g., scavenging vasoactive lipids/amines) that could inspire antiplatelet or anti-inflammatory lead molecules, though this remains exploratory for D7r4 specifically (Andersen 2010; https://doi.org/10.1016/j.toxicon.2009.11.002; Jablonka 2019; https://doi.org/10.1038/s41598-019-41848-0) (andersen2010structureandmechanism pages 8-9, jablonka2019functionalandstructural pages 9-10, jablonka2019functionalandstructural pages 1-2).
Expert opinions and analysis
- Andersen (2010) contextualizes D7 proteins as OBP-like salivary scavengers functionally analogous to lipocalins in other hematophagous lineages, with D7r4 exemplifying biogenic amine binding by short forms; the review integrates structural mechanisms (acidic residues and hydrophobic pockets) with physiological roles in mitigating hemostasis and inflammation (https://doi.org/10.1016/j.toxicon.2009.11.002) (andersen2010structureandmechanism pages 8-9).
- Jablonka et al. (2019) emphasize the evolutionary convergence of D7-mediated eicosanoid/amine scavenging, reinforcing the generality of the mechanism and the specialization of domains across D7 family members (https://doi.org/10.1038/s41598-019-41848-0) (jablonka2019functionalandstructural pages 9-10, jablonka2019functionalandstructural pages 1-2).
Limitations and knowledge gaps
- While D7r4’s biogenic amine-binding role is well-supported structurally and biochemically, quantitative kinetic parameters, precise in vivo concentrations achieved at bite sites, and D7r4-specific functional knockdown phenotypes were not available in the excerpts cited here. Likewise, few D7r4-specific publications from 2023–2024 were retrieved; ongoing D7 family research nonetheless supports the broader mechanistic framework (Mans 2007; Andersen 2010; Oseno 2022) (mans2007thecrystalstructure pages 1-1, andersen2010structureandmechanism pages 8-9, oseno2022characterizationofanopheles pages 1-2).
Embedded summary table with sources
| Aspect | Key finding | Primary source(s) with DOI/URL and year |
|---|---|---|
| Identity | Short-form D7 salivary protein (gene D7r4, AGAP008281; UniProt Q7PNF2). | Arcà et al., 2002 — https://doi.org/10.1046/j.0962-1075.2001.00309.x (Feb 2002) (arca2002aclusterof pages 1-2); Mans et al., 2007 — https://doi.org/10.1074/jbc.M706410200 (Dec 2007) (mans2007thecrystalstructure pages 1-1) |
| Organism | Found in the female malaria mosquito Anopheles gambiae; expressed in adult female salivary glands. | Arcà et al., 2002 — https://doi.org/10.1046/j.0962-1075.2001.00309.x (Feb 2002) (arca2002aclusterof pages 1-2); Oseno et al., 2022 — https://doi.org/10.1186/s13071-021-05130-5 (Jan 2022) (oseno2022characterizationofanopheles pages 1-2) |
| Family / Domains | Member of the insect OBP-like D7 family (PBP/GOBP-related fold); short-form single-domain D7 with ~8 α-helices and conserved disulfides. | Andersen, 2010 — https://doi.org/10.1016/j.toxicon.2009.11.002 (Dec 2010) (andersen2010structureandmechanism pages 8-9); Mans et al., 2007 — https://doi.org/10.1074/jbc.M706410200 (Dec 2007) (mans2007thecrystalstructure pages 1-1) |
| Structure | X-ray crystal structure solved (ligand-bound and unliganded forms reported); OBP-like fold with a defined ligand pocket (PDB coordinates deposited in Mans et al., 2007). | Mans et al., 2007 — https://doi.org/10.1074/jbc.M706410200 (Dec 2007) (mans2007thecrystalstructure pages 8-9) |
| Ligands / Biochemical specificity | Binds biogenic amines including serotonin, norepinephrine, histamine, and tryptamine; pocket forms H-bonds to amine/aromatic groups to sequester these mediators. | Mans et al., 2007 — https://doi.org/10.1074/jbc.M706410200 (Dec 2007) (mans2007thecrystalstructure pages 1-1); Andersen, 2010 — https://doi.org/10.1016/j.toxicon.2009.11.002 (Dec 2010) (andersen2010structureandmechanism pages 8-9) |
| Localization / Secretion | Secreted from female salivary glands into host skin during blood feeding. | Arcà et al., 2002 — https://doi.org/10.1046/j.0962-1075.2001.00309.x (Feb 2002) (arca2002aclusterof pages 1-2); Oseno et al., 2022 — https://doi.org/10.1186/s13071-021-05130-5 (Jan 2022) (oseno2022characterizationofanopheles pages 1-2) |
| Biological role / Pathways | Scavenges host biogenic amines at bite site to reduce vasoconstriction, platelet activation and inflammation, facilitating blood feeding. | Mans et al., 2007 — https://doi.org/10.1074/jbc.M706410200 (Dec 2007) (mans2007thecrystalstructure pages 1-1); Andersen, 2010 — https://doi.org/10.1016/j.toxicon.2009.11.002 (Dec 2010) (andersen2010structureandmechanism pages 8-9); Jablonka et al., 2019 — https://doi.org/10.1038/s41598-019-41848-0 (Mar 2019) (jablonka2019functionalandstructural pages 9-10) |
| Applications / Biomarker potential | Members of the D7 family (including D7r4) elicit human IgG responses; recombinant D7 proteins evaluated as serological markers of human–mosquito contact. | Oseno et al., 2022 — https://doi.org/10.1186/s13071-021-05130-5 (Jan 2022) (oseno2022characterizationofanopheles pages 1-2) |
| Recent developments / Comparative insights | Comparative structural/functional analyses show conserved ligand pockets across D7s and convergent acquisition of eicosanoid/amine binding in different lineages; limited D7r4-specific publications post-2022 but D7 family remains a focus for exposure markers and functional studies. | Jablonka et al., 2019 — https://doi.org/10.1038/s41598-019-41848-0 (Mar 2019) (jablonka2019functionalandstructural pages 1-2); Oseno et al., 2022 — https://doi.org/10.1186/s13071-021-05130-5 (Jan 2022) (oseno2022characterizationofanopheles pages 1-2) |
Table: Concise, evidence-linked summary of D7r4 (AGAP008281; UniProt Q7PNF2) covering identity, structure, ligands, localization, function, and applied uses, with primary literature DOIs and context citations for each entry.
Conclusion
D7r4 (AGAP008281; Q7PNF2) is a secreted, short-form D7 salivary protein of Anopheles gambiae with an OBP-like fold that binds and sequesters biogenic amines, notably serotonin and norepinephrine, reducing vasoconstriction, platelet activation, and inflammatory signaling at the bite site. Its structure, ligand interactions, and inferred physiological role in facilitating blood feeding are supported by crystallography and expert reviews. D7 family antigens, including D7r4, are already used in serological exposure assays, with ongoing research focused on leveraging these proteins for surveillance and as models for anti-hemostatic mechanisms (Mans 2007; https://doi.org/10.1074/jbc.M706410200; Andersen 2010; https://doi.org/10.1016/j.toxicon.2009.11.002; Oseno 2022; https://doi.org/10.1186/s13071-021-05130-5) (mans2007thecrystalstructure pages 1-1, andersen2010structureandmechanism pages 8-9, oseno2022characterizationofanopheles pages 1-2).
References
(arca2002aclusterof pages 1-2): B. Arcà, F. Lombardo, A. Lanfrancotti, L. Spanos, M. Veneri, C. Louis, and M. Coluzzi. A cluster of four d7‐related genes is expressed in the salivary glands of the african malaria vector anopheles gambiae. Insect Molecular Biology, Feb 2002. URL: https://doi.org/10.1046/j.0962-1075.2001.00309.x, doi:10.1046/j.0962-1075.2001.00309.x. This article has 64 citations and is from a peer-reviewed journal.
(mans2007thecrystalstructure pages 1-1): Ben J. Mans, Eric Calvo, José M.C. Ribeiro, and John F. Andersen. The crystal structure of d7r4, a salivary biogenic amine-binding protein from the malaria mosquito anopheles gambiae*. Journal of Biological Chemistry, 282:36626-36633, Dec 2007. URL: https://doi.org/10.1074/jbc.m706410200, doi:10.1074/jbc.m706410200. This article has 94 citations and is from a domain leading peer-reviewed journal.
(mans2007thecrystalstructure pages 8-9): Ben J. Mans, Eric Calvo, José M.C. Ribeiro, and John F. Andersen. The crystal structure of d7r4, a salivary biogenic amine-binding protein from the malaria mosquito anopheles gambiae*. Journal of Biological Chemistry, 282:36626-36633, Dec 2007. URL: https://doi.org/10.1074/jbc.m706410200, doi:10.1074/jbc.m706410200. This article has 94 citations and is from a domain leading peer-reviewed journal.
(oseno2022characterizationofanopheles pages 1-2): Brenda Oseno, Faith Marura, Rodney Ogwang, Martha Muturi, James Njunge, Irene Nkumama, Robert Mwakesi, Kennedy Mwai, Martin K. Rono, Ramadhan Mwakubambanya, Faith Osier, and James Tuju. Characterization of anopheles gambiae d7 salivary proteins as markers of human–mosquito bite contact. Parasites & Vectors, Jan 2022. URL: https://doi.org/10.1186/s13071-021-05130-5, doi:10.1186/s13071-021-05130-5. This article has 11 citations and is from a peer-reviewed journal.
(andersen2010structureandmechanism pages 8-9): John F. Andersen. Structure and mechanism in salivary proteins from blood-feeding arthropods. Toxicon : official journal of the International Society on Toxinology, 56 7:1120-9, Dec 2010. URL: https://doi.org/10.1016/j.toxicon.2009.11.002, doi:10.1016/j.toxicon.2009.11.002. This article has 61 citations.
(jablonka2019functionalandstructural pages 9-10): Willy Jablonka, Il Hwan Kim, Patricia H. Alvarenga, Jesus G. Valenzuela, Jose´ M. C. Ribeiro, and John F. Andersen. Functional and structural similarities of d7 proteins in the independently-evolved salivary secretions of sand flies and mosquitoes. Scientific Reports, Mar 2019. URL: https://doi.org/10.1038/s41598-019-41848-0, doi:10.1038/s41598-019-41848-0. This article has 34 citations and is from a peer-reviewed journal.
(jablonka2019functionalandstructural pages 1-2): Willy Jablonka, Il Hwan Kim, Patricia H. Alvarenga, Jesus G. Valenzuela, Jose´ M. C. Ribeiro, and John F. Andersen. Functional and structural similarities of d7 proteins in the independently-evolved salivary secretions of sand flies and mosquitoes. Scientific Reports, Mar 2019. URL: https://doi.org/10.1038/s41598-019-41848-0, doi:10.1038/s41598-019-41848-0. This article has 34 citations and is from a peer-reviewed journal.
id: Q7PNF2
gene_symbol: D7r4
product_type: PROTEIN
status: DRAFT
taxon:
id: NCBITaxon:7165
label: Anopheles gambiae
description: >-
D7r4 is a short-form salivary protein from female Anopheles gambiae mosquitoes that facilitates
blood feeding by binding and sequestering host biogenic amines (serotonin, histamine, norepinephrine,
and tryptamine). It functions as a "kratagonist" - capturing host signaling molecules with high
affinity to prevent their vasoconstrictive and inflammatory effects. The crystal structure of D7r4
has been solved (PDB: 2PQL, 2QEB, 2QEH, 2QEO, 2QEV) at high resolution (2.0-2.31 Angstroms),
revealing a modified OBP-like fold with eight alpha-helices, three disulfide bonds, and a binding
pocket adapted to amine ligands. D7r4 is secreted into saliva during blood feeding and belongs
to the PBP/GOBP (Pheromone/Odorant-Binding Protein) structural family but has evolved a distinct
function unrelated to olfaction.
existing_annotations:
- term:
id: GO:0005615
label: extracellular space
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
This annotation correctly describes D7r4's localization based on phylogenetic inference.
D7r4 is a secreted salivary protein with a signal peptide (residues 1-21) that is released
into the extracellular space during blood feeding [UniProt Q7PNF2].
action: ACCEPT
reason: >-
D7r4 is confirmed to be a secreted protein localized to female saliva. UniProt states
"SUBCELLULAR LOCATION: Secreted" with evidence from PMID:17913537. The IBA annotation from
phylogenetic trees is consistent with the IDA evidence for the same term. The protein
contains a signal peptide and is found in the extracellular salivary compartment from
which it is injected into the host during blood feeding [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: "-!- SUBCELLULAR LOCATION: Secreted"
- reference_id: PMID:17913537
supporting_text: >-
A proteomic and immunoproteomic analysis of anopheles and Aedes saliva allowed for
the identification of some antigens that were recognized by most of the exposed individuals
- term:
id: GO:0007608
label: sensory perception of smell
evidence_type: IBA
original_reference_id: GO_REF:0000033
review:
summary: >-
This annotation is INCORRECT. D7r4 is expressed exclusively in female salivary glands and
functions in blood feeding, not in olfactory perception. The IBA annotation was inferred
from homology to Drosophila odorant-binding proteins, but D7 proteins have evolved a
completely different function in mosquito saliva.
action: REMOVE
reason: >-
D7r4 is expressed specifically in female salivary glands, not olfactory tissues
[PMID:12062411, PMID:11841502]. UniProt explicitly states the tissue specificity. The D7
proteins have evolutionarily repurposed the OBP-like fold from olfactory function to
biogenic amine binding in saliva [PMID:16301315]. The IBA annotation appears to be based
on structural family membership (PBP/GOBP) shared with Drosophila odorant-binding proteins,
but this does not predict function. D7r4 binds serotonin, histamine, and norepinephrine -
not odorants [PMID:17928288]. Deep research confirms short-form D7s "predominantly bind
biogenic amines" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: >-
-!- TISSUE SPECIFICITY: Female saliva (at protein level) (PubMed:17913537).
Female salivary gland (PubMed:12062411). Not detected in female carcass
without salivary glands (PubMed:12062411). Not detected in male tissues
- reference_id: PMID:16301315
supporting_text: >-
The D7 salivary family of proteins is abundantly expressed in blood-feeding Diptera
and is distantly related to the odorant-binding protein superfamily
- term:
id: GO:0005549
label: odorant binding
evidence_type: IEA
original_reference_id: GO_REF:0000002
review:
summary: >-
This annotation is based on structural family membership (PBP/GOBP family via InterPro
IPR006170) but does not reflect the actual function of D7r4. The protein binds biogenic
amines (serotonin, histamine, norepinephrine, tryptamine), not odorants, and has no role
in olfaction. Crystal structures with bound ligands demonstrate this directly.
action: MODIFY
reason: >-
D7r4 belongs to the PBP/GOBP structural family (InterPro IPR006170), which led to this
IEA annotation. However, the D7 proteins have evolutionarily repurposed this fold for
binding biogenic amines in saliva, not odorants in antennae. D7r4 is expressed exclusively
in female salivary glands [PMID:12062411], not olfactory tissues. The actual molecular
functions are serotonin binding (GO:0051378), histamine binding (GO:0051381), norepinephrine
binding (GO:0051380), and tryptamine binding. Crystal structures of D7r4 with bound serotonin
(PDB:2QEH), histamine (PDB:2QEB), norepinephrine (PDB:2QEO), and tryptamine (PDB:2PQL)
demonstrate the actual binding specificity [PMID:17928288]. UniProt documents specific
binding residues for each ligand. The GO:0005549 definition "Binding to an odorant, any
substance capable of stimulating the sense of smell" does not apply - serotonin, histamine,
norepinephrine, and tryptamine are not odorants. Deep research confirms short-form D7s
"predominantly bind biogenic amines (serotonin/5-HT, histamine, epinephrine/norepinephrine)"
[file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
proposed_replacement_terms:
- id: GO:0051378
label: serotonin binding
- id: GO:0051381
label: histamine binding
- id: GO:0051380
label: norepinephrine binding
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Binds serotonin, noradrenaline, histamine and tryptamine
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein
from the malaria mosquito Anopheles gambiae
- term:
id: GO:0005576
label: extracellular region
evidence_type: IEA
original_reference_id: GO_REF:0000044
review:
summary: >-
This annotation correctly reflects the subcellular localization of D7r4 as a secreted
salivary protein. The IEA annotation from UniProt subcellular location vocabulary is
appropriate.
action: ACCEPT
reason: >-
D7r4 is a secreted protein with a signal peptide (residues 1-21) [UniProt Q7PNF2]. It is
released into the extracellular space (saliva) during blood feeding. The UniProt entry
confirms "SUBCELLULAR LOCATION: Secreted" with experimental evidence from PMID:17913537.
This is an appropriate CC annotation at the broader level. Deep research confirms D7
proteins are "secreted into saliva at the skin interface during probing/feeding"
[file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: "-!- SUBCELLULAR LOCATION: Secreted"
- term:
id: GO:0042311
label: vasodilation
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
This annotation is technically correct but represents the downstream physiological effect
rather than the direct biological process. D7r4 exhibits vasodilating activity by
sequestering vasoconstrictors (serotonin, norepinephrine) from the host.
action: ACCEPT
reason: >-
UniProt confirms D7r4 "Exhibits vasodilating activity" [UniProt Q7PNF2]. The mechanism is
indirect - D7r4 sequesters serotonin and norepinephrine, which are vasoconstrictors,
thereby preventing vasoconstriction and allowing vasodilation at the bite site.
PMID:16301315 states D7 proteins "bind serotonin with high affinity, as well as histamine
and norepinephrine" and that "Scavenging of host amines would antagonize their
vasoconstrictor, platelet-aggregating, and pain-inducing properties." While the
annotation captures a real physiological effect, it is a downstream consequence of
the kratagonist mechanism. However, since this is documented in the literature, it
should be retained. Deep research confirms biogenic amine scavenging "counteracts
platelet aggregation, vasoconstriction, and nociception during feeding"
[file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Exhibits vasodilating activity (PubMed:16301315)
- reference_id: PMID:16301315
supporting_text: >-
Scavenging of host amines would antagonize their vasoconstrictor,
platelet-aggregating, and pain-inducing properties
- term:
id: GO:0097746
label: blood vessel diameter maintenance
evidence_type: IEA
original_reference_id: GO_REF:0000043
review:
summary: >-
This annotation is a parent term of vasodilation and is somewhat redundant. D7r4 affects
blood vessel diameter by counteracting vasoconstriction through sequestration of host
biogenic amines.
action: KEEP_AS_NON_CORE
reason: >-
This annotation is inferred from the UniProt keyword "Vasodilator" via GO_REF:0000043.
While technically accurate as a broader term encompassing vasodilation, it is less
informative than GO:0042311 (vasodilation) which is also annotated. The primary mechanism
of D7r4 is sequestration of vasoconstrictive amines, with blood vessel diameter
maintenance being a downstream physiological consequence. This should be kept as a
non-core annotation since it accurately reflects a real biological effect but is not
the primary function of the protein.
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Exhibits vasodilating activity (PubMed:16301315)
- term:
id: GO:0005615
label: extracellular space
evidence_type: IDA
original_reference_id: PMID:17913537
review:
summary: >-
This is high-quality experimental evidence from mass spectrometry identification of D7r4
in female mosquito saliva. This annotation should be accepted as representing the
experimentally determined localization.
action: ACCEPT
reason: >-
PMID:17913537 provides direct experimental evidence (IDA - Inferred from Direct Assay)
for D7r4 localization in the extracellular space (saliva). The study performed proteomic
analysis of Anopheles gambiae saliva and identified D7r4 by mass spectrometry. UniProt
confirms "Female saliva (at protein level) (PubMed:17913537)" [UniProt Q7PNF2]. This
experimental evidence strongly supports the CC annotation.
supported_by:
- reference_id: PMID:17913537
supporting_text: >-
A proteomic and immunoproteomic analysis of anopheles and Aedes saliva allowed
for the identification of some antigens that were recognized by most of the
exposed individuals
- reference_id: UniProt:Q7PNF2
supporting_text: >-
-!- TISSUE SPECIFICITY: Female saliva (at protein level) (PubMed:17913537)
# PROPOSED NEW ANNOTATIONS
- term:
id: GO:0051378
label: serotonin binding
evidence_type: IDA
original_reference_id: PMID:17928288
review:
summary: >-
D7r4 binds serotonin with high affinity as demonstrated by direct binding assays and
crystal structure with bound serotonin (PDB:2QEH). This is a core molecular function.
action: NEW
reason: >-
UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315,
PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound serotonin
(PDB:2QEH) at 2.10 Angstrom resolution demonstrates the binding mode directly [PMID:17928288].
Specific binding residues are documented: Glu-28, His-56, Tyr-115, Asp-132, and Glu-135.
Mutagenesis studies confirm these residues are critical for serotonin binding - E28L and
E135L mutations significantly reduce serotonin binding [UniProt Q7PNF2]. GO:0051378
definition "Binding to serotonin (5-hydroxytryptamine), a monoamine neurotransmitter"
accurately describes this function. PMID:16301315 states "four of these five short D7
proteins and the D7 long form bind serotonin with high affinity".
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein
from the malaria mosquito Anopheles gambiae
- reference_id: PMID:16301315
supporting_text: >-
four of these five short D7 proteins and the D7 long form bind serotonin with
high affinity, as well as histamine and norepinephrine
- term:
id: GO:0051381
label: histamine binding
evidence_type: IDA
original_reference_id: PMID:17928288
review:
summary: >-
D7r4 binds histamine with high affinity as demonstrated by direct binding assays and
crystal structure with bound histamine (PDB:2QEB). This is a core molecular function.
action: NEW
reason: >-
UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315,
PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound histamine
(PDB:2QEB) at 2.00 Angstrom resolution demonstrates the binding mode directly [PMID:17928288].
Specific binding residues are documented: Tyr-115, Asp-132, and Glu-135. UniProt states
D7r4 "Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle
contraction" [UniProt Q7PNF2]. GO:0051381 definition "Binding to histamine, a physiologically
active amine" accurately describes this function. PMID:16301315 demonstrates histamine
binding activity.
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: >-
Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth
muscle contraction (PubMed:16301315)
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein
from the malaria mosquito Anopheles gambiae
- term:
id: GO:0051380
label: norepinephrine binding
evidence_type: IDA
original_reference_id: PMID:17928288
review:
summary: >-
D7r4 binds norepinephrine as demonstrated by direct binding assays and crystal structure
with bound norepinephrine (PDB:2QEO). This is a core molecular function.
action: NEW
reason: >-
UniProt confirms "Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315,
PubMed:17928288)" [UniProt Q7PNF2]. The crystal structure of D7r4 with bound norepinephrine
(PDB:2QEO) at 2.31 Angstrom resolution demonstrates the binding mode directly [PMID:17928288].
Specific binding residues are documented: Glu-28, Phe-43, Asp-132, and Glu-135. UniProt
states D7r4 "Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth
muscle contraction" [UniProt Q7PNF2]. GO:0051380 definition "Binding to norepinephrine"
accurately describes this function. PMID:16301315 states D7 short proteins bind
"norepinephrine" with high affinity.
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein
from the malaria mosquito Anopheles gambiae
- term:
id: GO:0035821
label: modulation of process of another organism
evidence_type: IDA
original_reference_id: PMID:16301315
review:
summary: >-
D7r4 modulates host hemostatic and inflammatory responses during blood feeding by
sequestering host biogenic amines. This is an appropriate BP annotation for the
cross-species effect.
action: NEW
reason: >-
D7r4 clearly modulates processes in the vertebrate host. UniProt states "Modulates blood
feeding of female mosquitoes on vertebrate species by binding and sequestering different
mediators involved in the host response" [UniProt Q7PNF2]. The GO:0035821 definition
"A process in which an organism effects a change in a biological process in another organism"
accurately captures this function. By sequestering serotonin, histamine, and norepinephrine
from the host, D7r4 prevents vasoconstriction, platelet aggregation, and inflammation.
PMID:16301315 confirms "Scavenging of host amines would antagonize their vasoconstrictor,
platelet-aggregating, and pain-inducing properties." Deep research describes D7 proteins
as "kratagonists - high-affinity scavengers of host small-molecule inflammatory and
hemostatic mediators" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: >-
Modulates blood feeding of female mosquitoes on vertebrate species by binding and
sequestering different mediators involved in the host response
- reference_id: PMID:16301315
supporting_text: >-
Scavenging of host amines would antagonize their vasoconstrictor,
platelet-aggregating, and pain-inducing properties
- term:
id: GO:1900047
label: negative regulation of hemostasis
evidence_type: IDA
original_reference_id: PMID:16301315
review:
summary: >-
D7r4 negatively regulates host hemostasis by sequestering biogenic amines that promote
platelet aggregation and vasoconstriction. This is a core biological process annotation.
action: NEW
reason: >-
By sequestering serotonin (which promotes platelet aggregation) and norepinephrine
(a vasoconstrictor), D7r4 negatively regulates the host hemostatic response at the
bite site. PMID:16301315 states "Scavenging of host amines would antagonize their
vasoconstrictor, platelet-aggregating, and pain-inducing properties." GO:1900047
definition "Any process that stops, prevents or reduces the frequency, rate or extent
of hemostasis" accurately captures this function. Deep research confirms biogenic amine
scavenging "counteracts platelet aggregation, vasoconstriction, and nociception during
feeding" [file:ANOGA/D7r1/D7r1-deep-research-falcon.md].
supported_by:
- reference_id: PMID:16301315
supporting_text: >-
Scavenging of host amines would antagonize their vasoconstrictor,
platelet-aggregating, and pain-inducing properties
references:
- id: GO_REF:0000002
title: Gene Ontology annotation through association of InterPro records with GO terms
findings: []
- id: GO_REF:0000033
title: Annotation inferences using phylogenetic trees
findings: []
- id: GO_REF:0000043
title: Gene Ontology annotation based on UniProtKB/Swiss-Prot keyword mapping
findings: []
- id: GO_REF:0000044
title: >-
Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary
mapping, accompanied by conservative changes to GO terms applied by UniProt
findings: []
- id: PMID:17913537
title: >-
Antibody response against saliva antigens of Anopheles gambiae and Aedes aegypti
in travellers in tropical Africa
findings:
- statement: D7r4 identified in female Anopheles gambiae saliva by mass spectrometry
supporting_text: >-
A proteomic and immunoproteomic analysis of anopheles and Aedes saliva allowed
for the identification of some antigens that were recognized by most of the
exposed individuals
- id: PMID:17928288
title: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein from the
malaria mosquito Anopheles gambiae
findings:
- statement: Crystal structures of D7r4 with bound biogenic amines solved at high resolution
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein
from the malaria mosquito Anopheles gambiae
- statement: D7r4 has a fold with eight alpha-helices and binding pocket for amines
supporting_text: >-
The D7 fold consists of an arrangement of eight alpha-helices stabilized by
- statement: Crystal structure reveals ligand binding pocket
supporting_text: >-
and structure of the ligand binding pocket. The pocket itself is lined by
- id: PMID:16301315
title: Function and evolution of a mosquito salivary protein family
findings:
- statement: D7 short proteins bind serotonin, histamine and norepinephrine with high affinity
supporting_text: >-
four of these five short D7 proteins and the D7 long form bind serotonin with
high affinity, as well as histamine and norepinephrine
- statement: Scavenging host amines antagonizes vasoconstriction and platelet aggregation
supporting_text: >-
Scavenging of host amines would antagonize their vasoconstrictor,
platelet-aggregating, and pain-inducing properties
- statement: D7 family is distantly related to odorant-binding proteins but has distinct function
supporting_text: >-
The D7 salivary family of proteins is abundantly expressed in blood-feeding Diptera
and is distantly related to the odorant-binding protein superfamily
- id: PMID:11841502
title: >-
A cluster of four D7-related genes is expressed in the salivary glands of the African
malaria vector Anopheles gambiae
findings:
- statement: D7r genes are expressed in adult female salivary glands
supporting_text: >-
Four genes expressed in the Anopheles gambiae adult female salivary glands and
similar in sequence to the Aedes aegypti D7 gene were identified
- id: PMID:12062411
title: Novel cDNAs encoding salivary proteins from the malaria vector Anopheles gambiae
findings:
- statement: D7r4 expression is specific to female salivary glands
supporting_text: >-
five corresponded to genes expressed specifically in female glands and their role may
possibly be linked to blood-feeding
- id: UniProt:Q7PNF2
title: UniProt entry for D7R4_ANOGA
findings:
- statement: D7r4 modulates blood feeding by binding host mediators
supporting_text: >-
Modulates blood feeding of female mosquitoes on vertebrate species by binding
and sequestering different mediators involved in the host response
- statement: Binds serotonin, noradrenaline, histamine and tryptamine
supporting_text: Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
- statement: Inhibits smooth muscle contraction induced by biogenic amines
supporting_text: >-
Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle
contraction (PubMed:16301315)
- statement: Exhibits vasodilating activity
supporting_text: Exhibits vasodilating activity (PubMed:16301315)
- statement: Expressed in female saliva and salivary gland
supporting_text: >-
-!- TISSUE SPECIFICITY: Female saliva (at protein level) (PubMed:17913537).
Female salivary gland (PubMed:12062411). Not detected in female carcass
without salivary glands (PubMed:12062411). Not detected in male tissues
- statement: Protein is secreted
supporting_text: "-!- SUBCELLULAR LOCATION: Secreted"
- id: file:ANOGA/D7r1/D7r1-deep-research-falcon.md
title: Deep research review of D7 protein family function and evolution
findings:
- statement: D7 proteins function as kratagonists that scavenge host signaling molecules
supporting_text: >-
D7 proteins are among the most abundant mosquito salivary proteins and function
as kratagonists—high-affinity scavengers of host small-molecule inflammatory
and hemostatic mediators
- statement: Short-form D7s bind biogenic amines
supporting_text: >-
short-form D7s (including D7r1) predominantly bind biogenic amines (serotonin/5-HT,
histamine, epinephrine/norepinephrine)
- statement: D7 proteins are secreted in saliva during feeding
supporting_text: >-
D7r1 is produced in adult female salivary glands and secreted in saliva at the
skin interface during probing/feeding
- statement: Crystal structure of D7r4 reveals binding pocket for biogenic amines
supporting_text: >-
The crystal structure of An. gambiae D7r4 revealed a modified OBP-like fold
(eight alpha-helices, three disulfide bonds) and a binding pocket adapted to
amine ligands
core_functions:
- description: >-
D7r4 functions as a kratagonist by binding and sequestering host biogenic amines (serotonin,
histamine, norepinephrine, and tryptamine) during blood feeding, thereby preventing
vasoconstriction, platelet aggregation, and inflammation at the feeding site.
molecular_function:
id: GO:0051378
label: serotonin binding
directly_involved_in:
- id: GO:1900047
label: negative regulation of hemostasis
- id: GO:0035821
label: modulation of process of another organism
- id: GO:0042311
label: vasodilation
locations:
- id: GO:0005615
label: extracellular space
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: >-
Modulates blood feeding of female mosquitoes on vertebrate species by binding and
sequestering different mediators involved in the host response
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein from
the malaria mosquito Anopheles gambiae
- description: >-
D7r4 binds histamine to prevent host inflammatory and vasodilatory responses during
blood feeding. Crystal structure at 2.0 Angstrom resolution demonstrates the binding mode.
molecular_function:
id: GO:0051381
label: histamine binding
directly_involved_in:
- id: GO:1900047
label: negative regulation of hemostasis
- id: GO:0035821
label: modulation of process of another organism
locations:
- id: GO:0005615
label: extracellular space
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: >-
Inhibits histamine-, serotonin- and partially noradrenaline-induced smooth muscle
contraction (PubMed:16301315)
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein from
the malaria mosquito Anopheles gambiae
- description: >-
D7r4 binds norepinephrine to counteract host vasoconstriction during blood feeding.
Crystal structure at 2.31 Angstrom resolution demonstrates the binding mode.
molecular_function:
id: GO:0051380
label: norepinephrine binding
directly_involved_in:
- id: GO:1900047
label: negative regulation of hemostasis
- id: GO:0035821
label: modulation of process of another organism
locations:
- id: GO:0005615
label: extracellular space
supported_by:
- reference_id: UniProt:Q7PNF2
supporting_text: Binds serotonin, noradrenaline, histamine and tryptamine (PubMed:16301315, PubMed:17928288)
- reference_id: UniProt:Q7PNF2
supporting_text: >-
The crystal structure of D7r4, a salivary biogenic amine-binding protein from
the malaria mosquito Anopheles gambiae
suggested_questions:
- question: >-
What are the binding affinities (Kd values) of D7r4 for each of its ligands (serotonin,
histamine, norepinephrine, tryptamine), and does it show preference for one over others?
experts:
- Andersen JF
- Mans BJ
- Ribeiro JM
- question: >-
Do the different D7 short forms (D7r1-5) have distinct ligand binding specificities that
enable non-redundant function during blood feeding?
experts:
- Calvo E
- Mans BJ
- question: >-
What is the structural basis for D7r4's ability to bind multiple chemically distinct
biogenic amines in the same binding pocket?
experts:
- Andersen JF
- Mans BJ
suggested_experiments:
- hypothesis: >-
D7r4 knockout mosquitoes will have reduced blood feeding efficiency due to enhanced
host hemostatic and inflammatory responses
description: >-
Generate D7r4 knockout A. gambiae using CRISPR and measure blood meal size, feeding time,
feeding success rate, and host inflammatory responses compared to wild-type controls
experiment_type: Gene knockout and feeding assay
- hypothesis: >-
D7r4 has evolved from odorant-binding proteins through changes in ligand binding specificity
description: >-
Perform comparative structural analysis and ancestral sequence reconstruction to determine
which amino acid changes are responsible for the shift from odorant to biogenic amine binding
experiment_type: Structural biology and molecular evolution
- hypothesis: >-
D7r4 and other D7 short forms have non-overlapping ligand preferences that together
provide comprehensive sequestration of host mediators
description: >-
Perform competitive binding assays with all D7 short forms (D7r1-5) against a panel of
biogenic amines to determine the binding specificity landscape of the D7 short form family
experiment_type: Binding assays and functional complementation