Affinage

CBLN3

Cerebellin-3 · UniProt Q6UW01

Length
205 aa
Mass
21.5 kDa
Annotated
2026-06-09
21 papers in source corpus 7 papers cited in narrative 7 extracted findings
Cross-family judge faithfulness: 6/6 claims corpus-supported (100%)

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

CBLN3 is a secreted C1q-family glycoprotein expressed selectively in cerebellar granule cells, where it functions as an obligate heteromeric partner of CBLN1 at parallel fiber–Purkinje cell synapses (PMID:10964938, PMID:17030622, PMID:19250438). Unlike CBLN1, CBLN2, and CBLN4, which autonomously assemble into homohexamers and are secreted independently, CBLN3 cannot form stable homomeric complexes and is retained in the endoplasmic reticulum when expressed alone (PMID:17030622, PMID:28714144). A single arginine residue in its N-terminal domain creates a steric clash that drives this ER retention; the clash is masked upon binding to CBLN1, permitting co-secretion of CBLN1–CBLN3 heteromers ('hide-and-run' mechanism) (PMID:17030622, PMID:17331201). Following secretion, CBLN1 and CBLN3 co-localize with the postsynaptic receptor GluRdelta2 at parallel fiber–Purkinje cell synaptic clefts (PMID:19250438). In the absence of CBLN1, CBLN3 is almost completely degraded, with regulated turnover of cerebellin proteins occurring through the endosomal/lysosomal pathway (PMID:17030622, PMID:18001291). CBLN3 expression onset is delayed to postnatal day 7–10, distinguishing it temporally from other family members (PMID:16930405).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2000 Medium

    Establishing that CBLN3 binds CBLN1 reframed CBLN3 from an isolated C1q-family protein into a partner-dependent member of a heteromeric system.

    Evidence Yeast two-hybrid screen with binding specificity assays

    PMID:10964938

    Open questions at the time
    • Stoichiometry and assembly architecture of the CBLN1-CBLN3 complex not resolved
    • Functional consequence of the interaction not addressed
  2. 2006 Medium

    Defining CBLN3 as selectively expressed in cerebellar granule cells with late postnatal onset localized its site of action and distinguished it temporally from related cerebellins.

    Evidence RT-PCR, Northern blot, and in situ hybridization across development

    PMID:16930405

    Open questions at the time
    • Does not address whether expression timing correlates with synapse formation
    • Protein-level localization not established
  3. 2006 High

    Identifying interaction-dependent secretion mediated by a single arginine resolved why CBLN3 cannot leave the cell alone and established the molecular basis of its obligate partnership with CBLN1.

    Evidence Knockout mouse lines (cbln1-null, cbln3-null, double-null), structural modeling, site-directed mutagenesis, and secretion assays

    PMID:17030622

    Open questions at the time
    • High-resolution structure of the steric clash and its masking not determined
    • Downstream synaptic function of secreted heteromer not directly tested here
  4. 2007 High

    Showing ER/cis-Golgi retention in heterologous cells and CBLN1-dependent partial secretion in primary granule cells confirmed the retention mechanism operates both in reconstituted systems and native neurons.

    Evidence Heterologous cell co-expression and immunohistochemistry in wild-type and cbln1-null granule cells

    PMID:17331201

    Open questions at the time
    • Efficiency and regulation of partial secretion not quantified
    • Trafficking route of the secreted complex to synapses unmapped
  5. 2007 Medium

    Demonstrating CBLN1 upregulation and endolysosomal localization in cbln3-null mice revealed that cerebellin protein levels are reciprocally regulated and turned over via lysosomal processing.

    Evidence Immunohistochemistry in cbln1-lacZ and cbln3-null mice with cathepsin D co-localization

    PMID:18001291

    Open questions at the time
    • Mechanism coupling complex formation to degradation routing unknown
    • Whether endolysosomal targeting is specific to uncomplexed protein not directly shown
  6. 2009 Medium

    Co-localization of CBLN1, CBLN3, and GluRdelta2 at parallel fiber–Purkinje cell synaptic clefts placed the secreted heteromer at a defined postsynaptic receptor site, indicating a trans-synaptic role.

    Evidence Light and electron microscopic immunohistochemistry with pepsin pretreatment and postembedding immunogold

    PMID:19250438

    Open questions at the time
    • Direct binding between the heteromer and GluRdelta2 not demonstrated here
    • Functional synaptic consequence of co-localization not tested
  7. 2017 Medium

    Comparative assembly analysis confirmed CBLN3 is uniquely unable to homo-assemble whereas CBLN1/2/4 form homohexamers, formalizing CBLN3's dependence within the family.

    Evidence Biochemical assembly and secretion assays in heterologous systems plus knockin reporter mice

    PMID:28714144

    Open questions at the time
    • Quantitative subunit composition of native heteromers not defined
    • Physiological role distinct from CBLN1 not isolated

Open questions

Synthesis pass · forward-looking unresolved questions
  • The specific synaptic function of CBLN3 and its individual contribution to GluRdelta2 signaling beyond serving as a CBLN1-dependent passenger remain unresolved.
  • No direct receptor-binding assay for CBLN3 itself
  • No behavioral or synaptic phenotype attributable specifically to CBLN3 reported in the corpus
  • Structural basis of the arginine steric clash unresolved

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0048018 receptor ligand activity 1
Localization
GO:0005576 extracellular region 2 GO:0005783 endoplasmic reticulum 2 GO:0005768 endosome 1
Pathway
R-HSA-9609507 Protein localization 2 R-HSA-112316 Neuronal System 1
Partners
Complex memberships
CBLN1-CBLN3 heteromer

Evidence

Reading pass · 7 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2000 CBLN3 was identified as a novel binding partner of CBLN1 via yeast two-hybrid screen. CBLN1 binds avidly to CBLN3 and also forms homomeric complexes, whereas CBLN3 homomeric association is weak. This interaction is specific, as C1qB bound neither CBLN1 nor CBLN3. Yeast two-hybrid screen, protein interaction assays The Journal of neuroscience Medium 10964938
2006 CBLN3 is secreted from cerebellar granule cells only when bound to CBLN1 (interaction-dependent secretion). In cbln1-null mice, Cbln3 is completely absent (degraded), whereas in cbln3-null mice, Cbln1 levels increase approximately sixfold. CBLN3 cannot form homomeric complexes and is retained in the endoplasmic reticulum when expressed alone. A single arginine residue in CBLN3 creates a steric clash that is masked upon Cbln1 binding ('hide-and-run' ER retention mechanism), conferring its unique secretion dependency. Knockout mouse analysis (cbln1-null, cbln3-null, double-null), structural modeling, site-directed mutagenesis, cell secretion assays Molecular and cellular biology High 17030622
2007 When expressed alone in mammalian heterologous cells, CBLN3 is not secreted but is retained in the endoplasmic reticulum or cis-Golgi due to its N-terminal domain. Co-expression of CBLN1 and CBLN3 results in partial secretion of CBLN3 together with CBLN1. In wild-type granule cells (which co-express CBLN1 and CBLN3), CBLN3 is partially secreted and reaches postsynaptic sites on Purkinje cell dendrites; in cbln1-null granule cells, CBLN3 is almost completely degraded. Heterologous cell expression, co-expression assays, immunohistochemistry in wild-type and cbln1-null granule cells The European journal of neuroscience High 17331201
2006 CBLN3 mRNA expression in the brain is selective to cerebellar granule cells throughout development, with onset as late as postnatal day 7-10, distinguishing it from other Cbln family members which appear earlier in development. RT-PCR, Northern blot, high-resolution in situ hybridization The European journal of neuroscience Medium 16930405
2009 CBLN1 and CBLN3 co-localize with GluRdelta2 at parallel fiber-Purkinje cell synaptic clefts, as revealed by antigen-exposing immunohistochemical methods. CBLN1 accumulates in the synaptic cleft specifically at PF-PC synapses (not at other PC synapses), and co-localizes almost completely with CBLN3 and GluRdelta2 at these sites. Light and electron microscopic immunohistochemistry with pepsin pretreatment and postembedding immunogold The European journal of neuroscience Medium 19250438
2007 In cbln3-null mice, CBLN1-like immunoreactivity in the cerebellum is dramatically increased (consistent with CBLN1 upregulation when not complexed with CBLN3), but CLI is unchanged in extracerebellar neurons. CBLN1 localizes to the endolysosomal compartment (co-localizing with cathepsin D) in neurons, suggesting that regulated degradation of Cbln proteins occurs through endosome/lysosome processing. Immunohistochemistry, cbln1-lacZ transgenic mice, cbln3-null mice, co-localization with lysosomal marker cathepsin D The European journal of neuroscience Medium 18001291
2017 CBLN3 requires CBLN1 for assembly and secretion, unlike CBLN1, CBLN2, and CBLN4 which autonomously assemble into homohexamers. This property distinguishes CBLN3 functionally from other cerebellin family members. Biochemical assembly and secretion assays in heterologous expression systems, knockin reporter mice The Journal of comparative neurology Medium 28714144

Source papers

Stage 0 corpus · 21 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2006 Distinct expression of Cbln family mRNAs in developing and adult mouse brains. The European journal of neuroscience 92 16930405
2000 Cbln3, a novel member of the precerebellin family that binds specifically to Cbln1. The Journal of neuroscience : the official journal of the Society for Neuroscience 68 10964938
2017 Cerebellins are differentially expressed in selective subsets of neurons throughout the brain. The Journal of comparative neurology 56 28714144
2006 Cbln1 is essential for interaction-dependent secretion of Cbln3. Molecular and cellular biology 49 17030622
2007 Characterization of a transneuronal cytokine family Cbln--regulation of secretion by heteromeric assembly. The European journal of neuroscience 47 17331201
2009 Cbln1 accumulates and colocalizes with Cbln3 and GluRdelta2 at parallel fiber-Purkinje cell synapses in the mouse cerebellum. The European journal of neuroscience 31 19250438
2007 Mapping of Cbln1-like immunoreactivity in adult and developing mouse brain and its localization to the endolysosomal compartment of neurons. The European journal of neuroscience 31 18001291
2008 Expression of precerebellins in cultured rat calvaria osteoblast-like cells. International journal of molecular medicine 16 18813864
2009 Precerebellin-related genes and precerebellin 1 peptide in endocrine glands of the rat - pattern of their expression. International journal of molecular medicine 14 19082514
2009 Insulinostatic activity of cerebellin--evidence from in vivo and in vitro studies in rats. Regulatory peptides 12 19481574
2020 GNG13 Is a Potential Marker of the State of Health of Alzheimer's Disease Patients' Cerebellum. Journal of molecular neuroscience : MN 10 33057964
2010 Identification of cerebellin2 in chick and its preferential expression by subsets of developing sensory neurons and their targets in the dorsal horn. The Journal of comparative neurology 9 20506477
2019 Mouse models and strain-dependency of Chédiak-Higashi syndrome-associated neurologic dysfunction. Scientific reports 8 31043676
2024 Biomarker discovery in progressive supranuclear palsy from human cerebrospinal fluid. Clinical proteomics 5 39342078
2020 Comparative transcriptome analysis of normal and CD44-deleted mouse brain under chronic infection with Toxoplasma gondii. Acta tropica 5 32544399
2021 The porcine cerebellin gene family. Gene 3 34274480
2026 Association of prenatal glycemic marker cumulative exposure with placental DNA methylation change. The Journal of clinical endocrinology and metabolism 1 41507059
2026 Biomarker for craving and acamprosate treatment response in patients with alcohol use disorder: insights from multi-omics. Molecular psychiatry 0 41741704
2026 Structural Architecture and Evolutionary Conservation of Cerebellin-Mediated Trans-Synaptic Signaling. Synapse (New York, N.Y.) 0 41995212
2026 Genome-wide DNA methylation signatures in blood associated with pediatric obesity. Clinical epigenetics 0 42121001
2025 Integrative multi-omics analysis of druggable genes for therapeutic target identification in polycystic ovary syndrome. Journal of ovarian research 0 41388545

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