Ryanodine Receptor 3 (RyR3 Protein)

Ryanodine Receptor 3 (RyR3 Protein)

Introduction

Ryanodine receptor 3 (RyR3) (encoded by the [RYR3 gene](/genes/ryr3)) is an intracellular calcium release channel expressed in brain, smooth muscle, and diaphragm. In the nervous system, RyR3 is enriched in the [hippocampus](/brain-regions/hippocampus) and [striatum](/brain-regions/striatum), where it modulates calcium-dependent synaptic plasticity and learning.

Overview

RyR3 is the third isoform of the ryanodine receptor family, forming a homotetrameric ER calcium release channel of similar size to [RyR1](/proteins/ryr1-protein) and [RyR2](/proteins/ryr2-protein)^[1]. Each subunit is 4,872 amino acids. RyR3 has the most restricted tissue distribution of the three RyR isoforms but is notably enriched in specific brain regions, particularly the [hippocampus](/brain-regions/hippocampus) CA1 region, [striatum](/brain-regions/striatum), and [thalamus](/brain-regions/thalamus)^[2]. RyR3 knockout mice show enhanced hippocampal [LTP](/mechanisms/long-term-potentiation) and impaired spatial learning, suggesting RyR3 normally provides a brake on calcium signaling that refines plasticity. [@bhatt2014]

<div class="infobox infobox-protein"> [@bhatt2002]

Ryanodine Receptor 3 (RyR3 Protein)

Introduction

Ryanodine receptor 3 (RyR3) (encoded by the [RYR3 gene](/genes/ryr3)) is an intracellular calcium release channel expressed in brain, smooth muscle, and diaphragm. In the nervous system, RyR3 is enriched in the [hippocampus](/brain-regions/hippocampus) and [striatum](/brain-regions/striatum), where it modulates calcium-dependent synaptic plasticity and learning.

Overview

RyR3 is the third isoform of the ryanodine receptor family, forming a homotetrameric ER calcium release channel of similar size to [RyR1](/proteins/ryr1-protein) and [RyR2](/proteins/ryr2-protein)^[1]. Each subunit is 4,872 amino acids. RyR3 has the most restricted tissue distribution of the three RyR isoforms but is notably enriched in specific brain regions, particularly the [hippocampus](/brain-regions/hippocampus) CA1 region, [striatum](/brain-regions/striatum), and [thalamus](/brain-regions/thalamus)^[2]. RyR3 knockout mice show enhanced hippocampal [LTP](/mechanisms/long-term-potentiation) and impaired spatial learning, suggesting RyR3 normally provides a brake on calcium signaling that refines plasticity. [@bhatt2014]

<div class="infobox infobox-protein"> [@bhatt2002]

| | | [@bhatt2017]
|---|---|
| Protein Name | Ryanodine Receptor 3 (RyR3) |
| Gene | [RYR3](/genes/ryr3) |
| UniProt ID | [Q15413](https://www.uniprot.org/uniprot/Q15413) |
| Molecular Weight | ~552 kDa (monomer), ~2.2 MDa (tetramer) |
| Length | 4,872 amino acids |
| Subcellular Localization | ER membrane |
| Function | Intracellular Ca²⁺ release channel |

</div>

Function

Neuronal Calcium Regulation

RyR3 modulates intracellular calcium dynamics in specific neuronal populations^[2]:

• Hippocampal CA1: Enriched in [dendritic spines](/mechanisms/dendritic-spines) where it modulates calcium signals underlying LTP/LTD
• Striatal [neurons](/entities/neurons): Contributes to dopamine-mediated calcium signaling
• Thalamic relay neurons: Participates in oscillatory calcium activity
• Neonatal brain: Highly expressed during brain development, suggesting developmental roles

Distinct Properties

RyR3 differs from RyR1 and RyR2 in several functional aspects^[1]:

• Lower Ca²⁺ sensitivity: Higher threshold for calcium-induced calcium release
• No inactivation at high Ca²⁺: Unlike RyR1, RyR3 does not inactivate at micromolar Ca²⁺
• Lower single-channel conductance: Smaller unitary Ca²⁺ currents
• Functional brake: RyR3 may dampen excessive ER Ca²⁺ release, preventing calcium overload

Role in Neurodegeneration

Synaptic Plasticity and Memory

RyR3 dysregulation affects processes impaired in neurodegenerative diseases^[3]:

• Spatial memory: RyR3 KO mice have impaired Morris water maze performance
• Social memory: Deficits in social recognition memory in RyR3 KO
• Fear conditioning: Altered amygdala-dependent learning
• LTP refinement: Loss of RyR3 causes exaggerated LTP → impaired learning (too much plasticity is as bad as too little)

Disease Connections

• [Alzheimer's disease](/diseases/alzheimers-disease): RyR3 expression altered in AD hippocampus; calcium dysregulation contributes to synaptic failure^[4]
• [Huntington's disease](/diseases/huntington-disease): RyR3 is enriched in striatal medium spiny neurons that degenerate in HD; mutant [huntingtin](/proteins/huntingtin) sensitizes RyR channels
• Aging: RyR3 expression declines with aging in hippocampus, potentially contributing to age-related memory decline

Protein Interactions

| Interactor | Type | Function |
|-----------|------|----------|
| FKBP12 | Stabilizer | Calstabin-1; stabilizes closed channel state |
| Calmodulin | Modulator | Calcium-dependent regulation |
| [RyR1](/proteins/ryr1-protein) | Hetero-oligomer | May form heteromeric channels in brain |
| [RyR2](/proteins/ryr2-protein) | Co-expressed | Complementary ER calcium release in hippocampus |

See Also

• [RYR3 Gene](/genes/ryr3)
• [RyR1 Protein](/proteins/ryr1-protein)
• [RyR2 Protein](/proteins/ryr2-protein)
• [Calcium Dysregulation in Neurodegeneration](/mechanisms/calcium-dysregulation-neurodegeneration)
• [Hippocampus](/brain-regions/hippocampus)

External Links

• [RyR3 - UniProt](https://www.uniprot.org/uniprot/Q15413)
• [RYR3 - NCBI Gene](https://www.ncbi.nlm.nih.gov/gene/6263)

References