Affinage

POC1B

POC1 centriolar protein homolog B · UniProt Q8TC44

Length
478 aa
Mass
53.7 kDa
Annotated
2026-04-28
19 papers in source corpus 8 papers cited in narrative 8 extracted findings

Mechanistic narrative

Synthesis pass · prose summary of the discoveries below

POC1B is a centriolar scaffold protein essential for centriole integrity, ciliogenesis, and cell division. It forms heterodimers with POC1A in the centriole lumen, where its WD40 domain positions near the centriole wall to organize an inner interaction network with POC5, FAM161A, and MDM1 that maintains centriole microtubule architecture; disruption of POC1B alone causes microtubule defects, and co-deletion with POC1A leads to centriole disintegration (PMID:39543170, PMID:23015594). POC1B localizes to basal bodies of primary and photoreceptor sensory cilia and interacts with FAM161A at the connecting cilium base; loss of POC1B in zebrafish and mice causes shortened photoreceptor outer segments, retinal degeneration, and defective sperm flagella formation, establishing it as a ciliopathy gene required for both retinal integrity and male fertility (PMID:25018096, PMID:25044745, PMID:37070736). POC1B is phosphorylated during mitosis with independent roles in cell cycle progression, and its mRNA is post-transcriptionally regulated via o8G oxidative modification to sustain centrosome integrity in cardiomyocytes (PMID:23015594, PMID:41325109).

Mechanistic history

Synthesis pass · year-by-year structured walk · 7 steps
  1. 2012 High

    Resolving whether POC1 paralogs have distinct centriolar roles, this study showed POC1B stably associates with parental centrioles, is uniquely phosphorylated in mitosis, and is individually required for cell proliferation, while co-depletion with POC1A causes centriole integrity loss and spindle defects.

    Evidence RNAi depletion with isoform-specific antibodies, live-cell imaging, and cell cycle analysis in human cells

    PMID:23015594

    Open questions at the time
    • The phosphorylation sites on POC1B and their functional consequences during mitosis were not mapped
    • Whether POC1B's centriolar role is purely structural or involves enzymatic/regulatory activity was not established
    • Interaction partners of POC1B within the centriole were unknown
  2. 2014 High

    Linking POC1B to ciliopathy, two studies demonstrated its localization to basal bodies of primary cilia and photoreceptor connecting cilia, its physical interaction with FAM161A, and that loss of POC1B in zebrafish causes photoreceptor degeneration and shortened connecting cilia.

    Evidence Yeast two-hybrid, co-immunoprecipitation, immunohistochemistry in human/mouse retina, zebrafish morpholino knockdown with mRNA rescue

    PMID:25018096 PMID:25044745

    Open questions at the time
    • The precise mechanism by which POC1B supports connecting cilium formation versus maintenance was not distinguished
    • Whether FAM161A interaction is direct or within a larger complex was unresolved
    • The structural basis for disease-causing missense variants disrupting basal body localization was unknown
  3. 2015 Medium

    Extending the ciliary phenotype, zebrafish poc1b knockdown produced multi-organ ciliopathy features including impaired visual function, shortened Kupffer's vesicle cilia, and heart defects, broadening POC1B's role beyond the retina.

    Evidence Zebrafish morpholino knockdown with visual behavior assays and multi-organ phenotyping

    PMID:26188096

    Open questions at the time
    • Whether these phenotypes reflect a general basal body defect versus tissue-specific POC1B functions was unclear
    • Morpholino off-target effects were not ruled out with genetic mutants
  4. 2019 Medium

    Addressing how POC1B contributes to centriole assembly, Drosophila studies showed Poc1B is recruited to the centriole base in a Sas-6-dependent manner and stabilizes Sas-6-nucleated centriolar structures.

    Evidence Genetic epistasis with Poc1 mutant flies and Sas-6 co-overexpression assays in Drosophila

    PMID:31387336

    Open questions at the time
    • Direct biochemical interaction between Poc1B and Sas-6 was not demonstrated
    • Whether this stabilization mechanism is conserved in vertebrates was untested
  5. 2023 High

    Establishing POC1B as required for male fertility, a human frameshift variant and corresponding CRISPR knock-in mouse model demonstrated that loss of POC1B protein causes oligoasthenoteratozoospermia with defective acrosome and flagella.

    Evidence Whole-exome sequencing of infertile patient, CRISPR/Cas9 knock-in mouse, transmission electron microscopy of sperm

    PMID:37070736

    Open questions at the time
    • Whether the flagellar defect is due to basal body dysfunction or axonemal assembly failure was not resolved
    • Rescue experiments restoring POC1B in the mouse model were not performed
  6. 2024 High

    Providing a molecular architecture for POC1B function, this study revealed POC1A-POC1B heterodimers organize a luminal interaction network with POC5, FAM161A, and MDM1 that positions these proteins near the centriole wall to maintain microtubule integrity.

    Evidence Super-resolution microscopy, co-immunoprecipitation network mapping, single and double genetic knockouts with electron microscopy of centriole ultrastructure

    PMID:39543170

    Open questions at the time
    • Atomic-resolution structure of the POC1A-POC1B heterodimer and its interfaces with POC5/FAM161A/MDM1 is lacking
    • How the luminal network mechanistically stabilizes centriole wall microtubules is not defined
    • Whether this network is remodeled during centriole maturation or ciliogenesis was not addressed
  7. 2026 Medium

    Revealing a post-transcriptional regulatory layer, POC1B mRNA was identified as a target of o8G oxidative modification repressed by HNRNPH1, with the piRNA MCPPIR antagonizing this repression to maintain POC1B protein levels and centrosome integrity in cardiomyocytes.

    Evidence o8G-RIP-seq, RNA pull-down with mass spectrometry, cardiomyocyte-specific HNRNPH1 knockout and MCPPIR genetic ablation/overexpression in mice

    PMID:41325109

    Open questions at the time
    • Whether o8G-mediated regulation of POC1B operates in cell types beyond cardiomyocytes is unknown
    • The specific o8G-modified sites on POC1B mRNA that mediate HNRNPH1 binding were not mapped
    • Independent replication of the MCPPIR-POC1B regulatory axis has not been reported

Open questions

Synthesis pass · forward-looking unresolved questions
  • Key unresolved questions include the atomic structure of the POC1A-POC1B heterodimer, the identity and functional significance of POC1B's mitotic phosphorylation sites, and the mechanism by which the luminal centriole network transitions to support basal body function during ciliogenesis.
  • No high-resolution structural data for the POC1B-containing luminal complex exist
  • The kinase(s) responsible for POC1B mitotic phosphorylation are unidentified
  • Whether POC1B has tissue-specific interaction partners in photoreceptors versus sperm is unexplored

Mechanism profile

Synthesis pass · controlled-vocabulary classification · explore literature graph →
Molecular activity
GO:0005198 structural molecule activity 2
Localization
GO:0005815 microtubule organizing center 5 GO:0005929 cilium 3
Pathway
R-HSA-1852241 Organelle biogenesis and maintenance 3 R-HSA-1640170 Cell Cycle 1
Partners
FAM161AHNRNPH1MDM1POC1APOC5SAS6
Complex memberships
POC1A-POC1B heterodimerPOC1A-POC1B-POC5-FAM161A-MDM1 luminal network

Evidence

Reading pass · 8 per-paper findings extracted from the source corpus
Year Finding Method Journal Conf PMIDs
2012 POC1B localizes to centrioles and spindle poles; a fraction remains stably associated with parental centrioles while preventing incorporation into nascent centrioles when depleted. Co-depletion of POC1A and POC1B causes loss of nascent centriole integrity and maturation, failure of centriole duplication, and defects in spindle organization (unequal or monopolar spindles). POC1B, but not POC1A, is phosphorylated during mitosis, and depletion of POC1B alone is sufficient to perturb cell proliferation. Isoform-specific antibodies, RNAi depletion, live-cell imaging, immunofluorescence, cell cycle analysis in human cells Journal of cell science High 23015594
2014 POC1B wild-type protein localizes to the basal body of the primary cilium in retinal pigment epithelium cells; disease-associated missense variants p.Arg106Pro and p.Gln67del abolish this basal body localization. POC1B interacts with FAM161A (a ciliopathy-associated protein at the base of the photoreceptor connecting cilium), and this interaction is disrupted by the p.Arg106Pro and p.Gln67del variants. Overexpression in hTERT-RPE1 cells with immunofluorescence localization; yeast two-hybrid screening of human retinal cDNA library; co-immunoprecipitation; colocalization assays; zebrafish morpholino knockdown with mRNA rescue American journal of human genetics High 25018096
2014 POC1B localizes to the basal body and centriole adjacent to the connecting cilium of photoreceptors in human and mouse retina, and also to synapses of the outer plexiform layer. Knockdown of Poc1b in zebrafish causes shortened and reduced photoreceptor connecting cilia and retinal degeneration, establishing POC1B as required for retinal integrity and ciliogenesis. Immunohistochemistry in human and mouse retina; zebrafish morpholino knockdown Human mutation Medium 25044745
2015 Poc1b localizes to centrioles and spindle bundles during cell cycle progression and to the basal body of photoreceptor sensory cilia. Morpholino knockdown of poc1b in zebrafish results in delayed retinal laminar development, shortened photoreceptor outer segments, impaired visual function, and ciliopathy-associated defects (small eyes, curved body axis, heart defects, shortened cilia in Kupffer's vesicle). Tagged recombinant protein expression in renal epithelial cells and rat retina; zebrafish morpholino knockdown with visual behavior assays Biochemical and biophysical research communications Medium 26188096
2019 In Drosophila, Poc1B is recruited to the giant centriole base during atypical centriole (PCL) formation in a Sas-6-dependent manner. Poc1B and Sas-6 colocalize in the PCL/centriole core, and co-overexpression of Poc1B and Sas-6 induces formation of PCL-like structures; Poc1 mutant flies show disruption of these ectopic structures, indicating that Poc1 proteins stabilize centriolar structures formed by Sas-6. Immunofluorescence, genetic epistasis (Poc1 mutant flies), overexpression assays in Drosophila Cells Medium 31387336
2023 A homozygous frameshift variant (c.151delG) in POC1B causes loss of POC1B protein in sperm cells. In poc1b knock-in mice, this mutation results in oligoasthenoteratozoospermia with abnormal acrosome and flagella formation, establishing POC1B as required for normal sperm development and flagellar cilia integrity. Whole-exome sequencing; protein analysis of patient biological samples; CRISPR/Cas9 knock-in mouse model; testicular histology; transmission electron microscopy of testes and sperm Human molecular genetics High 37070736
2024 POC1B forms heterodimers with POC1A within the centriole lumen, where the WD40 domain of POC1B localizes close to the centriole wall. POC1A-POC1B heterodimers organize an interaction network with POC5 and microtubule-binding proteins FAM161A and MDM1; FAM161A and MDM1 bind to POC1A-POC1B and likely position the POC5 tetramer near the centriole wall. Disruption of POC1B alone causes centriole microtubule defects, and deletion of both POC1A and POC1B causes centriole disintegration. Structural localization (super-resolution microscopy), co-immunoprecipitation/interaction network mapping, domain-function analysis, genetic deletion (POC1A, POC1B single and double knockouts) with electron microscopy of centriole ultrastructure Nature communications High 39543170
2026 POC1B mRNA is subject to o8G (8-oxoguanosine) oxidative modification; the piRNA MCPPIR prevents HNRNPH1-mediated repression of POC1B mRNA, thereby maintaining POC1B protein levels. POC1B acts downstream in the MCPPIR-HNRNPH1-POC1B axis to maintain centrosome integrity and promote cardiomyocyte proliferation. RNA pull-down, mass spectrometry (HNRNPH1 as binding partner of MCPPIR), o8G-RNA immunoprecipitation sequencing, cardiomyocyte-specific HNRNPH1 knockout mice, MCPPIR genetic ablation and overexpression in mice Cardiovascular research Medium 41325109

Source papers

Stage 0 corpus · 19 papers · ranked by NIH iCite citations
Year Title Journal Citations PMID
2014 Disruption of the basal body protein POC1B results in autosomal-recessive cone-rod dystrophy. American journal of human genetics 68 25018096
2012 Poc1A and Poc1B act together in human cells to ensure centriole integrity. Journal of cell science 67 23015594
2014 Mutation of POC1B in a severe syndromic retinal ciliopathy. Human mutation 61 25044745
2014 Novel recessive cone-rod dystrophy caused by POC1B mutation. JAMA ophthalmology 30 24945461
2019 Phenotypical Characteristics of POC1B-Associated Retinopathy in Japanese Cohort: Cone Dystrophy With Normal Funduscopic Appearance. Investigative ophthalmology & visual science 22 31390656
2017 Case of cone dystrophy with normal fundus appearance associated with biallelic POC1B variants. Ophthalmic genetics 19 29220607
2021 Clinical Characteristics of POC1B-Associated Retinopathy and Assignment of Pathogenicity to Novel Deep Intronic and Non-Canonical Splice Site Variants. International journal of molecular sciences 16 34065499
2024 An interaction network of inner centriole proteins organised by POC1A-POC1B heterodimer crosslinks ensures centriolar integrity. Nature communications 15 39543170
2023 Homozygous frameshift variant in POC1B causes male infertility with oligoasthenoteratozoospermia in human and mice. Human molecular genetics 14 37070736
2018 Novel compound heterozygous mutation in the POC1B gene underlie peripheral cone dystrophy in a Chinese family. Ophthalmic genetics 14 29377742
2015 Knockdown of poc1b causes abnormal photoreceptor sensory cilium and vision impairment in zebrafish. Biochemical and biophysical research communications 14 26188096
2019 Poc1B and Sas-6 Function Together during the Atypical Centriole Formation in Drosophila melanogaster. Cells 13 31387336
2021 A homozygous POC1B variant causes recessive cone-rod dystrophy. Ophthalmic genetics 7 33657974
2026 MCPPIR promotes cardiomyocyte proliferation and cardiac repair via o8G oxidation of POC1B mRNA. Cardiovascular research 3 41325109
2023 Phenotypic and genotypic features of POC1B-associated cone dystrophy. Ophthalmic genetics 3 37246743
2022 Seroreactivity against retinal proteins in a case of POC1B gene associated cone dystrophy with normal funduscopic appearance: a systematic approach to diagnosis. Ophthalmic genetics 2 36094084
2025 Severe Joubert syndrome in family with homozygous POC1B p.Arg106Pro variant is due to a co-inherited deep-intronic mutation in the neighboring CEP290 gene. HGG advances 0 40170356
2025 POC1B-associated cone-rod dystrophy with bilateral optic disc swelling: A novel clinical observation. American journal of ophthalmology case reports 0 41293231
2025 Long non-coding RNA POC1B-AS1 depletion represses colorectal cancer progression through the microRNA-625-5p/FOXK1 axis. American journal of translational research 0 41552296