Component
GCAP1 / GUCA1A
Calcium/magnesium-sensing guanylyl cyclase activating protein 1.
3 recorded relationships. Experimental role, claim status and evidence remain attached to each record.
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.
Other things that act on it
Enzymes, hormones, genes, and other components with a recorded effect. These are not nutrients, so they do not count toward the arrows above. Each finding names the chapter that recorded it.
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.
What acts on it
Magnesium-bound GCAP1, rather than metal-free GCAP1, activated RetGC1 under low-calcium assay conditions.
Experimental context and source evidence
- cross_nutrient
- Mg2+ and Ca2+ regulate a sensor in vitamin A-dependent phototransduction recovery.
- experimental_model
- Purified protein metal-binding and cyclase assays
- limitations
- No dietary magnesium deficiency or human night-vision outcome was measured.
- nutrient_topic
- Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
- organism
- Recombinant protein biochemical system
- plain_language
- Magnesium occupancy lets the calcium sensor stimulate cGMP recovery.
- primary_references
- [peshenko-2006] Ca2+ and Mg2+ binding properties of GCAP-1. Evidence that Mg2+-bound form is the physiological activator of photoreceptor guanylyl cyclase (2006). https://pubmed.ncbi.nlm.nih.gov/16793776/ DOI: 10.1074/jbc.M600257200
- tissue_or_cell_type
- Photoreceptor-protein model
Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 973–983
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Purified protein metal-binding and cyclase assays · source_derived_draft · unverified_draft
### a-vision-magnesium-gcap1 Magnesium-bound GCAP1, rather than metal-free GCAP1, activated RetGC1 under low-calcium assay conditions. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Magnesium occupancy lets the calcium sensor stimulate cGMP recovery. organism: Recombinant protein biochemical system tissue_or_cell_type: Photoreceptor-protein model experimental_model: Purified protein metal-binding and cyclase assays limitations: No dietary magnesium deficiency or human night-vision outcome was measured. cross_nutrient: Mg2+ and Ca2+ regulate a sensor in vitamin A-dependent phototransduction recovery. [peshenko-2006] Ca2+ and Mg2+ binding properties of GCAP-1. Evidence that Mg2+-bound form is the physiological activator of photoreceptor guanylyl cyclase (2006). https://pubmed.ncbi.nlm.nih.gov/16793776/ DOI: 10.1074/jbc.M600257200
Complete structured claim and evidence
Where it participates (unsigned role)
Removing GCAP1 and GCAP2 abolished calcium dependence of retinal guanylyl cyclase activity in mouse assays.
Experimental context and source evidence
- cross_nutrient
- Calcium-sensitive GCAPs regulate recovery downstream of the vitamin A photopigment.
- experimental_model
- Retinal homogenate cyclase activity at low versus high free calcium
- limitations
- Evidence for intracellular feedback, not calcium intake or blood-calcium thresholds.
- nutrient_topic
- Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
- organism
- Mus musculus
- plain_language
- GCAP sensors connect calcium changes to cGMP synthesis.
- primary_references
- [mendez-2001] Role of guanylate cyclase-activating proteins (GCAPs) in setting the flash sensitivity of rod photoreceptors (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC55558/ DOI: 10.1073/pnas.171308998
- tissue_or_cell_type
- Retina
Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 961–971
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Retinal homogenate cyclase activity at low versus high free calcium · source_derived_draft · unverified_draft
### a-vision-calcium-cyclase-feedback Removing GCAP1 and GCAP2 abolished calcium dependence of retinal guanylyl cyclase activity in mouse assays. Condition category: normal nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: GCAP sensors connect calcium changes to cGMP synthesis. organism: Mus musculus tissue_or_cell_type: Retina experimental_model: Retinal homogenate cyclase activity at low versus high free calcium limitations: Evidence for intracellular feedback, not calcium intake or blood-calcium thresholds. cross_nutrient: Calcium-sensitive GCAPs regulate recovery downstream of the vitamin A photopigment. [mendez-2001] Role of guanylate cyclase-activating proteins (GCAPs) in setting the flash sensitivity of rod photoreceptors (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC55558/ DOI: 10.1073/pnas.171308998
Complete structured claim and evidenceGCAP-null mouse rods showed larger and slower dark-adapted flash responses than wild-type rods.
Experimental context and source evidence
- availability_state
- machinery_impairment Imported condition classification; unverified.
- cross_nutrient
- Loss of calcium feedback changes a vitamin A-initiated response without proving nutrient deficiency.
- experimental_model
- Single-rod suction-electrode recordings
- limitations
- GCAP2 restoration did not fully restore normal kinetics; isoforms are not interchangeable.
- nutrient_topic
- Vitamin A research collection; topical membership is not evidence of a direct dietary effect. · Vitamin A
- organism
- Mus musculus
- plain_language
- Without these calcium sensors, rod responses last longer.
- primary_references
- [mendez-2001] Role of guanylate cyclase-activating proteins (GCAPs) in setting the flash sensitivity of rod photoreceptors (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC55558/ DOI: 10.1073/pnas.171308998
- tissue_or_cell_type
- Rod photoreceptors
- trigger_kind
- machinery_impairment Imported condition classification; unverified.
Vitamin A: forms, mechanisms, deficiency and excess (2026-09-17) · lines 985–995
AI-assisted literature curation; primary study URLs and scope retained in the document and extraction. Not publisher full text. · supports · Single-rod suction-electrode recordings · source_derived_draft · unverified_draft
### a-vision-gcap-response GCAP-null mouse rods showed larger and slower dark-adapted flash responses than wild-type rods. Condition category: machinery_impairment nutrient_topic: Vitamin A research collection; topical membership is not evidence of a direct dietary effect. plain_language: Without these calcium sensors, rod responses last longer. organism: Mus musculus tissue_or_cell_type: Rod photoreceptors experimental_model: Single-rod suction-electrode recordings limitations: GCAP2 restoration did not fully restore normal kinetics; isoforms are not interchangeable. cross_nutrient: Loss of calcium feedback changes a vitamin A-initiated response without proving nutrient deficiency. [mendez-2001] Role of guanylate cyclase-activating proteins (GCAPs) in setting the flash sensitivity of rod photoreceptors (2001). https://pmc.ncbi.nlm.nih.gov/articles/PMC55558/ DOI: 10.1073/pnas.171308998
Complete structured claim and evidence
The events it takes part in
A mechanism often involves more than two components. These are the full events, with every participant and its role.
Situations it appears in
Low-supply and faulty-machinery situations recorded in the chapters where this component plays a part.
In the sources
Preserved passages that mention this component, quoted exactly. Open one to read it in context.
Open hypotheses
Proposed ideas that involve this component. They are labeled as hypotheses and do not change any recorded statement.
This is a research prototype built from draft material. It is not medical advice, and its statements still await verification against the original studies.