CACNB3 is a cytoplasmic regulatory beta subunit of voltage-gated calcium channels. It associates with pore-forming alpha subunits to modulate channel trafficking, voltage dependence and calcium influx.
Summary: CACNB3 is the cytoplasmic regulatory beta subunit rather than the pore-forming alpha subunit. Calcium channel regulator activity directly captures its mechanism.
Reason: CACNB3 is the cytoplasmic regulatory beta subunit rather than the pore-forming alpha subunit. Calcium channel regulator activity directly captures its mechanism. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: The beta subunit acts on the cytoplasmic side of the calcium-channel complex.
Reason: The beta subunit acts on the cytoplasmic side of the calcium-channel complex. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:34234349}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: Human functional coexpression establishes beta3 as a calcium-channel complex subunit; the horse sequence is strongly conserved.
Reason: Human functional coexpression establishes beta3 as a calcium-channel complex subunit; the horse sequence is strongly conserved. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: Human functional coexpression establishes beta3 as a calcium-channel complex subunit; the horse sequence is strongly conserved.
Reason: Human functional coexpression establishes beta3 as a calcium-channel complex subunit; the horse sequence is strongly conserved. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: A regulatory beta subunit participates in calcium transport by modulating channel gating and surface expression, without forming the pore.
Reason: A regulatory beta subunit participates in calcium transport by modulating channel gating and surface expression, without forming the pore. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: A regulatory beta subunit participates in calcium transport by modulating channel gating and surface expression, without forming the pore.
Reason: A regulatory beta subunit participates in calcium transport by modulating channel gating and surface expression, without forming the pore. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
The cloned H beta 3 subunit was further expressed in Xenopus oocytes to demonstrate its ability to modulate VDCC activity.
GO:0008331 high voltage-gated calcium channel activity
IBA GO_REF:0000033
MODIFY
Summary: The beta subunit regulates high-voltage-activated channels; its standalone molecular activity is regulation rather than pore conduction.
Reason: The beta subunit regulates high-voltage-activated channels; its standalone molecular activity is regulation rather than pore conduction. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: Association with membrane calcium-channel complexes supports membrane association of this cytoplasmic accessory subunit.
Reason: Association with membrane calcium-channel complexes supports membrane association of this cytoplasmic accessory subunit. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:34234349}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: Regulation of calcium-channel activity contributes to transmembrane calcium transport.
Reason: Regulation of calcium-channel activity contributes to transmembrane calcium transport. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
Summary: The beta3 regulatory subunit can assemble with L-type channel alpha subunits in a functional channel complex.
Reason: The beta3 regulatory subunit can assemble with L-type channel alpha subunits in a functional channel complex. This assessment transfers characterized mammalian biology to the selected horse sequence with the sequence limitations stated in the comparison.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
The cloned H beta 3 subunit was further expressed in Xenopus oocytes to demonstrate its ability to modulate VDCC activity.
Core Functions
CACNB3 is a cytoplasmic regulatory beta subunit of voltage-gated calcium channels. It associates with pore-forming alpha subunits to modulate channel trafficking, voltage dependence and calcium influx.
CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}.
The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence.
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
Assessment of 1 ProtNLM GO predictions for the selected horse CACNB3 protein, using mammalian experimental findings and an explicit comparison of the horse sequence.
Review score: 2 = concordant with evidence; 1 = uncertain; 0 = discordant with evidence. This is an assessment score, not a model probability.
GO:0034765 regulation of monoatomic ion transmembrane transportGO_BP
COR — Correct novel prediction Review score: 2/2
Prediction method: ProtNLM2 · Version: UniProt API snapshot 2026-09-08
Review rationale: Human CACNB3 coexpression experiments demonstrate modulation of voltage-dependent calcium channels (PMID:8119293). The horse protein spans the complete human reference with 97.11% identity, supporting conservation of the regulatory beta-subunit architecture. Regulation of ion transmembrane transport is therefore supported without assigning a pore-forming function to the beta subunit. The exact process term is absent from target GOA, which contains calcium-transport and channel-complex annotations; this is target annotation novelty, not evidence about model training. Training-set membership is unknown.
Supporting Evidence:
file:human/CACNB3/CACNB3-uniprot.txt: "CC -!- FUNCTION: Regulatory subunit of the voltage-gated calcium channel that CC gives rise to L-type calcium currents (PubMed:8119293). Increases CC CACNA1B peak calcium current and shifts the voltage dependencies of CC channel activation and inactivation (By similarity). Increases CACNA1C CC peak calcium current and shifts the voltage dependencies of channel CC activation and inactivation (By similarity). CC {ECO:0000250|UniProtKB:P54287, ECO:0000250|UniProtKB:Q9MZL3, CC ECO:0000269|PubMed:8119293}."
file:HORSE/CACNB3/CACNB3-bioinformatics/RESULTS.md: "The horse sequence A0A5F5PZM5 (517 residues) aligns to human P54284 (484 residues) with 97.11% identity across 484 paired residues. Paired coverage is 100.0% of the human sequence and 93.62% of the horse sequence."
PMID:8119293: "The cloned H beta 3 subunit was further expressed in Xenopus oocytes to demonstrate its ability to modulate VDCC activity."
📚 Additional Documentation
Notes
(CACNB3-notes.md)
CACNB3: paired evidence notes
Human reference: https://www.uniprot.org/uniprotkb/P54284/entry
The cloned H beta 3 subunit was further expressed in Xenopus oocytes to demonstrate its ability to modulate VDCC activity.
The horse sequence comparison is in CACNB3-bioinformatics/RESULTS.md. Transfer is assessed for this exact accession; human biochemical evidence is not equine experimental validation.