Component

Retinol-loaded RBP4

RBP4 carrying retinol; distinct from apo-RBP4 and total circulating RBP4.

4 recorded relationships. Experimental role, claim status and evidence remain attached to each record.

Read recorded mechanisms Open recursive mind map

How nutrients influence it

Every nutrient with a recorded effect on this component, credited to the nutrient that acted rather than the chapter that recorded it. Open a nutrient to see the findings and the conditions they were measured under.

How nutrients reach it in more than one step

Chains of two or more recorded steps that end here, grouped by the nutrient they start from. Each step is a separate finding, so a chain is a route a mechanism could take, not proof that it does.

Tracing routes…

What it does

Every recorded relationship this component is part of, grouped by its role. Plain wording comes first; the technical statement follows.

Recorded relationships

What acts on it

  1. STRA6 was identified as a high-affinity membrane receptor for retinol-binding protein.

    Retinol uptake receptor STRA6 → Retinol-loaded RBP4 source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Abstract
    experimental_model
    Receptor isolation from bovine retinal pigment epithelium and cellular uptake assays.
    exposure
    RBP-binding purification and receptor-expression assays.
    limitations
    Identification in RPE does not make STRA6 mandatory for every tissue.
    nutrient_topic
    Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
    organism
    Bos taurus receptor-isolation material and transfected cells
    outcome
    STRA6 was identified as a high-affinity membrane receptor for retinol-binding protein.
    plain_language
    Cells recognize circulating retinol through its carrier protein.
    primary_references
    [va-kawaguchi-2007] A membrane receptor for retinol binding protein mediates cellular uptake of vitamin A (2007). https://pubmed.ncbi.nlm.nih.gov/17255476/ DOI: 10.1126/science.1136244
    tissue_or_cell_type
    Retinal pigment epithelium and plasma membrane

    Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 430–442

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Receptor isolation from bovine retinal pigment epithelium and cellular uptake assays. · source_derived_draft · unverified_draft

    ### va-stra6-rbp-binding STRA6 was identified as a high-affinity membrane receptor for retinol-binding protein. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Cells recognize circulating retinol through its carrier protein. organism: Bos taurus receptor-isolation material and transfected cells tissue_or_cell_type: Retinal pigment epithelium and plasma membrane experimental_model: Receptor isolation from bovine retinal pigment epithelium and cellular uptake assays. limitations: Identification in RPE does not make STRA6 mandatory for every tissue. exposure: RBP-binding purification and receptor-expression assays. outcome: STRA6 was identified as a high-affinity membrane receptor for retinol-binding protein. evidence_location: Abstract [va-kawaguchi-2007] A membrane receptor for retinol binding protein mediates cellular uptake of vitamin A (2007). https://pubmed.ncbi.nlm.nih.gov/17255476/ DOI: 10.1126/science.1136244
    Complete structured claim and evidence

Where it participates (unsigned role)

  1. Coexpression of LRAT enhanced STRA6-mediated retinol uptake by coupling transport to ester storage.

    Lecithin:retinol acyltransferase / LRAT → STRA6-mediated retinol uptake source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Figure 1
    experimental_model
    Transfected-cell radioretinol uptake and real-time retinol-release assays.
    exposure
    STRA6 with or without LRAT; radiolabeled holo-RBP uptake.
    limitations
    No single intracellular protein was absolutely required for STRA6 activity. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted.
    nutrient_topic
    Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
    organism
    Mammalian transfected cells
    outcome
    Coexpression of LRAT enhanced STRA6-mediated retinol uptake by coupling transport to ester storage.
    plain_language
    Retinol esterification helps keep inward uptake moving.
    primary_references
    [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    tissue_or_cell_type
    Plasma membrane and intracellular retinoid compartment

    Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 459–471

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Transfected-cell radioretinol uptake and real-time retinol-release assays. · source_derived_draft · unverified_draft

    ### va-lrat-couples-stra6 Coexpression of LRAT enhanced STRA6-mediated retinol uptake by coupling transport to ester storage. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Retinol esterification helps keep inward uptake moving. organism: Mammalian transfected cells tissue_or_cell_type: Plasma membrane and intracellular retinoid compartment experimental_model: Transfected-cell radioretinol uptake and real-time retinol-release assays. limitations: No single intracellular protein was absolutely required for STRA6 activity. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted. exposure: STRA6 with or without LRAT; radiolabeled holo-RBP uptake. outcome: Coexpression of LRAT enhanced STRA6-mediated retinol uptake by coupling transport to ester storage. evidence_location: Figure 1 [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    Complete structured claim and evidence

  2. Cellular RBP1 enhanced STRA6-mediated uptake of RBP-bound retinol.

    Cellular retinol-binding protein 1 / RBP1 → STRA6-mediated retinol uptake source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Figure 1
    experimental_model
    Transfected-cell radioretinol uptake and real-time retinol-release assays.
    exposure
    STRA6 plus CRBP-I compared with STRA6 alone.
    limitations
    Coupling is supported, but absolute RBP1 dependence is not. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted.
    nutrient_topic
    Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
    organism
    Mammalian transfected cells
    outcome
    Cellular RBP1 enhanced STRA6-mediated uptake of RBP-bound retinol.
    plain_language
    An intracellular retinol-binding protein helps retain delivered vitamin A.
    primary_references
    [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    tissue_or_cell_type
    Plasma membrane and cytoplasm

    Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 473–485

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Transfected-cell radioretinol uptake and real-time retinol-release assays. · source_derived_draft · unverified_draft

    ### va-rbp1-couples-stra6 Cellular RBP1 enhanced STRA6-mediated uptake of RBP-bound retinol. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: An intracellular retinol-binding protein helps retain delivered vitamin A. organism: Mammalian transfected cells tissue_or_cell_type: Plasma membrane and cytoplasm experimental_model: Transfected-cell radioretinol uptake and real-time retinol-release assays. limitations: Coupling is supported, but absolute RBP1 dependence is not. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted. exposure: STRA6 plus CRBP-I compared with STRA6 alone. outcome: Cellular RBP1 enhanced STRA6-mediated uptake of RBP-bound retinol. evidence_location: Figure 1 [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    Complete structured claim and evidence

  3. STRA6 accelerated retinol release from extracellular RBP in real-time assays.

    Retinol uptake receptor STRA6 → All-trans-retinol source_derived_draftungraded
    Experimental context and source evidence
    evidence_location
    Abstract
    experimental_model
    Transfected-cell radioretinol uptake and real-time retinol-release assays.
    exposure
    Retinol-loaded RBP and STRA6 expression.
    limitations
    In vitro transport mechanism; no organism-wide flux estimate. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted.
    nutrient_topic
    Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
    organism
    Mammalian transfected-cell preparations
    outcome
    STRA6 accelerated retinol release from extracellular RBP in real-time assays.
    plain_language
    The receptor unloads retinol from its blood carrier.
    primary_references
    [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    tissue_or_cell_type
    Plasma membrane
    transport_direction
    extracellular holo-RBP4 to membrane/cell

    Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 444–457

    AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Transfected-cell radioretinol uptake and real-time retinol-release assays. · source_derived_draft · unverified_draft

    ### va-stra6-retinol-release STRA6 accelerated retinol release from extracellular RBP in real-time assays. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: The receptor unloads retinol from its blood carrier. organism: Mammalian transfected-cell preparations tissue_or_cell_type: Plasma membrane experimental_model: Transfected-cell radioretinol uptake and real-time retinol-release assays. limitations: In vitro transport mechanism; no organism-wide flux estimate. Cell-line species were not resolved in the retrieved abstract/figure evidence; no species-specific extension is asserted. exposure: Retinol-loaded RBP and STRA6 expression. outcome: STRA6 accelerated retinol release from extracellular RBP in real-time assays. evidence_location: Abstract transport_direction: extracellular holo-RBP4 to membrane/cell [va-kawaguchi-2011] Receptor-mediated cellular uptake mechanism that couples to intracellular storage (2011). https://pmc.ncbi.nlm.nih.gov/articles/PMC3199320/ DOI: 10.1021/cb200178w
    Complete structured claim and evidence

In the sources

Preserved passages that mention this component, quoted exactly. Open one to read it in context.

    This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.

    Evidence, AI assistance and curation standards