Existing Annotations Review

GO Term	Evidence	Action	Reason
GO:0042555 MCM complex	IBA GO_REF:0000033	ACCEPT	Summary: MCM-4 is a subunit of the heterohexameric MCM2-7 (MCM) complex. This is the defining cellular component for the protein and is strongly supported phylogenetically (the IBA is propagated across MCM2-7 orthologs from yeast to mammals) and by direct C. elegans evidence. Reason: Core, well-established localization. MCM-4 is an integral subunit of the MCM2-7 pre-RC / replicative helicase complex, supported by orthology and by direct study in C. elegans. Supporting Evidence: PMID:21146520 lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex.
GO:0003697 single-stranded DNA binding	IBA GO_REF:0000033	ACCEPT	Summary: As a subunit of the MCM2-7 replicative helicase, MCM-4 contributes to binding and translocation along single-stranded DNA during origin unwinding and fork progression. ssDNA binding is a conserved property of the MCM ring. Reason: Conserved molecular function of MCM subunits within the helicase ring; consistent with the replicative helicase role established for C. elegans MCM-4. The activity is a property of the assembled complex, but the enables qualifier at the subunit level reflects standard MCM annotation practice. Supporting Evidence: PMID:21146520 encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex
GO:0017116 single-stranded DNA helicase activity	IBA GO_REF:0000033	ACCEPT	Summary: MCM-4 contributes to the ssDNA-translocating helicase activity of the MCM2-7 / CMG complex that unwinds template DNA at replication forks. The contributes_to qualifier correctly reflects that helicase activity is a property of the assembled hexamer, not the isolated subunit. Reason: Conserved replicative helicase function, supported by orthology and by the C. elegans demonstration that MCM-4 is a component of the replicative helicase complex. The contributes_to qualifier is appropriate for a single MCM subunit. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication file:worm/mcm-4/mcm-4-deep-research-falcon.md MCM proteins carry ATP-binding motifs and are attributed ATPase and helicase activities, with ATP hydrolysis within the MCM ring driving DNA translocation and unwinding in CMG.
GO:0006271 DNA strand elongation involved in DNA replication	IBA GO_REF:0000033	ACCEPT	Summary: The MCM2-7/CMG helicase unwinds DNA ahead of the replication fork during elongation, and MCM-4 is required for DNA synthesis in C. elegans somatic lineages. This process annotation is consistent with the replicative helicase role. Reason: Strand elongation requires continued fork unwinding by the MCM2-7 helicase; well supported by orthology and by the requirement of mcm-4 for postembryonic DNA synthesis. Supporting Evidence: PMID:21146520 C. elegans lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages, while entry into mitosis continues
GO:1902975 mitotic DNA replication initiation	IBA GO_REF:0000033	ACCEPT	Summary: MCM2-7 licensing of origins is the central event in initiation of mitotic (S-phase) DNA replication, and MCM-4 is required for this process. The term captures the licensing/initiation role of the complex in the mitotic cell cycle. Reason: Replication licensing by MCM2-7 is required for initiation of mitotic DNA replication; supported by orthology and by the C. elegans replication defect on loss of mcm-4. Supporting Evidence: PMID:21146520 Our results support a conserved function of mcm-4 in replication licensing, DNA synthesis and the replication checkpoint
GO:0000727 double-strand break repair via break-induced replication	IBA GO_REF:0000033	MARK AS OVER ANNOTATED	Summary: This IBA propagates a break-induced replication (BIR) role across the MCM family. BIR uses the replicative helicase to copy DNA from a broken end, so MCM involvement is mechanistically plausible, but there is no direct C. elegans evidence that MCM-4 functions specifically in BIR, and this is a narrow, specialized repair pathway relative to the core replication role. Reason: BIR is a specialized DNA double-strand break repair pathway; while the replicative helicase can be co-opted for BIR, this phylogenetically-propagated term over-specifies the role of MCM-4 in C. elegans, where the documented functions are bulk DNA replication and the replication checkpoint. No organism-specific evidence supports a dedicated BIR function. Retain as a recognized but non-core/over-annotated process rather than a core function. Supporting Evidence: PMID:21146520 Our results support a conserved function of mcm-4 in replication licensing, DNA synthesis and the replication checkpoint
GO:0003677 DNA binding	IEA GO_REF:0000002	ACCEPT	Summary: MCM-4 binds DNA as part of the MCM2-7 helicase ring that encircles and translocates along DNA. This InterPro2GO electronic annotation is broad but correct. Reason: DNA binding is a general, correct parent term for the MCM helicase. The more specific single-stranded DNA binding annotation is also present; the broader IEA is acceptable. Supporting Evidence: PMID:31283754 MCM-4 is a component of the minichromosome maintenance complex which is responsible for licensing origins for DNA replication
GO:0003678 DNA helicase activity	IEA GO_REF:0000120	ACCEPT	Summary: MCM-4 is part of the MCM2-7/CMG replicative DNA helicase. This is a core molecular function, correctly captured by this electronic annotation (and mirrored by ISS and IBA annotations to the more specific ssDNA helicase term). Reason: Correct core function for an MCM subunit; the activity is a property of the assembled complex but DNA helicase activity is the standard MF annotation for MCM proteins. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication file:worm/mcm-4/mcm-4-deep-research-falcon.md an MCM4/6/7 subcomplex exhibits intrinsic ssDNA-dependent ATP hydrolysis
GO:0005524 ATP binding	IEA GO_REF:0000002	ACCEPT	Summary: MCM-4 contains a conserved MCM AAA+ ATPase module (Walker A/B motifs) that binds ATP; ATP binding and hydrolysis power the MCM2-7 helicase. The UniProt record annotates EC 3.6.4.12 ATP-dependent DNA helicase activity by similarity. This electronic annotation is correct. Reason: Direct consequence of the conserved AAA+ ATPase domain; ATP binding is a standard, well-supported molecular function for MCM subunits. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication
GO:0005634 nucleus	IEA GO_REF:0000044	ACCEPT	Summary: MCM-4 acts on nuclear chromatin during DNA replication and is detected in the nucleus / on chromatin in dividing cells. Nuclear localization is consistent with its function and is also directly supported (IDA). Reason: Correct subcellular localization, corroborated by direct C. elegans evidence (IDA, PMID:21146520) showing chromatin/nuclear association in dividing cells. Supporting Evidence: PMID:21146520 The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase
GO:0005694 chromosome	IEA GO_REF:0000044	ACCEPT	Summary: MCM-4 associates with chromatin/chromosomes as part of the pre-RC and replisome. This electronic annotation is corroborated by direct experimental evidence of chromatin association in late anaphase. Reason: Correct localization; MCM2-7 is loaded onto origins on chromosomes and MCM-4 is observed associating with chromatin (EXP/IDA, PMID:21146520). Supporting Evidence: PMID:21146520 associates with chromatin in late anaphase
GO:0006260 DNA replication	IEA GO_REF:0000002	ACCEPT	Summary: A core biological process for MCM-4, which is required for DNA replication as a subunit of the replicative helicase. Directly supported by the C. elegans loss-of-function replication defect. Reason: Central, well-established function; mcm-4 mutants fail postembryonic DNA synthesis. Supporting Evidence: PMID:21146520 lin-6 mutants lack DNA synthesis in postembryonic somatic cell lineages
GO:0006270 DNA replication initiation	IEA GO_REF:0000002	ACCEPT	Summary: MCM2-7 licensing/loading at origins is required for replication initiation, and MCM-4 is part of this process. Consistent with the conserved licensing role demonstrated for C. elegans mcm-4. Reason: Correct process annotation for an MCM subunit acting in origin licensing and initiation. Supporting Evidence: PMID:21146520 Our results support a conserved function of mcm-4 in replication licensing, DNA synthesis and the replication checkpoint
GO:0016887 ATP hydrolysis activity	IEA GO_REF:0000116	ACCEPT	Summary: The MCM AAA+ module hydrolyzes ATP to drive DNA translocation/unwinding by the MCM2-7 ring. This Rhea-mapped electronic annotation is correct; ATP hydrolysis powers the replicative helicase. Reason: Direct consequence of the conserved ATPase domain; ATP hydrolysis powers the MCM2-7/CMG helicase that unwinds origin DNA. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication file:worm/mcm-4/mcm-4-deep-research-falcon.md MCM proteins carry ATP-binding motifs and are attributed ATPase and helicase activities, with ATP hydrolysis within the MCM ring driving DNA translocation and unwinding in CMG.
GO:0042555 MCM complex	IEA GO_REF:0000002	ACCEPT	Summary: Electronic (InterPro2GO) annotation to the MCM complex, duplicating the well-supported IBA/NAS/ISS annotations to the same component. Correct. Reason: Correct core localization; redundant with the experimentally and phylogenetically supported MCM complex annotations. Supporting Evidence: PMID:21146520 encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex
GO:0005694 chromosome	EXP PMID:21146520 C. elegans MCM-4 is a general DNA replication and checkpoint...	ACCEPT	Summary: Direct experimental evidence that MCM-4 associates with chromatin (chromosomes) in dividing C. elegans cells, observed in late anaphase. This is the experimental basis for the chromosome localization. Reason: Strong direct evidence from the primary functional paper; MCM-4 is chromatin/chromosome-associated as expected for a pre-RC subunit. The cell-cycle dynamics (chromatin-associated only at specific cell-cycle windows) are consistent with regulated MCM loading. Supporting Evidence: PMID:21146520 The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase file:worm/mcm-4/mcm-4-deep-research-falcon.md MCM-4 is nuclear during interphase, becomes diffuse upon nuclear envelope breakdown and is not associated with metaphase chromatin, and then reassociates with chromatin in late anaphase
GO:0016887 ATP hydrolysis activity	ISS GO_REF:0000024	ACCEPT	Summary: ATP hydrolysis activity inferred from sequence/structural similarity to MCM4 orthologs bearing the conserved AAA+ ATPase module. Consistent with the Rhea-mapped IEA annotation to the same term. Reason: Correct; the conserved MCM ATPase domain supports ATP hydrolysis as part of the helicase mechanism. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication
GO:0006279 premeiotic DNA replication	NAS PMID:21146520 C. elegans MCM-4 is a general DNA replication and checkpoint...	KEEP AS NON CORE	Summary: Premeiotic (germline) DNA replication requires the MCM2-7 helicase. In mcm-4 mutants the germline retains substantial replication/division capacity from maternal/zygotic contribution, but MCM-4 is nonetheless a required replication component, including in germline lineages. This NAS annotation reflects a curator narrative statement. Reason: The core role of MCM-4 is general (mitotic) DNA replication; premeiotic replication is one specific replication context. The paper notes the germline continues replication relatively well in zygotic mcm-4 mutants, so this is a legitimate but specialized, non-core facet rather than the defining function. Supporting Evidence: PMID:21146520 In contrast to somatic cells in mcm-4 mutants, the gonad continues DNA replication and cell division until late larval development
GO:0042555 MCM complex	NAS PMID:21146520 C. elegans MCM-4 is a general DNA replication and checkpoint...	ACCEPT	Summary: Curator (NAS) statement that MCM-4 is a component of the MCM complex, drawn from the primary paper that identifies it as an MCM2-7 subunit. Duplicates the strongly supported IBA/IEA/ISS MCM complex annotations. Reason: Correct core localization, directly stated in the cited paper. Supporting Evidence: PMID:21146520 encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex
GO:0003678 DNA helicase activity	ISS GO_REF:0000024	ACCEPT	Summary: DNA helicase activity inferred from sequence similarity to MCM4 orthologs, with the contributes_to qualifier correctly indicating that the activity belongs to the assembled MCM2-7 ring rather than the isolated subunit. Reason: Correct core molecular function; the contributes_to qualifier is the appropriate framing for a single MCM subunit within the helicase. Supporting Evidence: PMID:31283754 is the DNA helicase complex responsible for unwinding the DNA at the origins of replication
GO:0003697 single-stranded DNA binding	ISS GO_REF:0000024	ACCEPT	Summary: ssDNA binding inferred from similarity to MCM4 orthologs; the MCM2-7 ring engages single-stranded DNA during unwinding. Duplicates the IBA annotation to the same term with a contributes_to qualifier. Reason: Conserved MCM function; contributes_to appropriately reflects activity at the complex level. Supporting Evidence: PMID:21146520 encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex
GO:0042555 MCM complex	ISS GO_REF:0000024	ACCEPT	Summary: MCM complex membership inferred from sequence similarity to MCM4 orthologs. Duplicates the experimentally and phylogenetically supported MCM complex annotations. Reason: Correct core localization, redundant with stronger evidence lines. Supporting Evidence: PMID:21146520 encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex
GO:0005515 protein binding	IPI PMID:31283754 The demethylase NMAD-1 regulates DNA replication and repair ...	KEEP AS NON CORE	Summary: MCM-4 was identified in NMAD-1 immunoprecipitation/mass-spectrometry as a putative NMAD-1-binding protein and shown to bind NMAD-1 directly in vitro (recombinant His-tagged NMAD-1 pulldown of MCM-4). Notably, the authors were unable to confirm the NMAD-1/MCM-4 interaction in vivo (only the NMAD-1/TOP-2 interaction was confirmed in vivo). The direct in vitro binding supports the IPI annotation, but protein binding is an uninformative molecular function term per curation guidelines and does not, on its own, define a specific activity. Reason: The direct NMAD-1/MCM-4 interaction is supported by in vitro recombinant binding assays, but the in vivo interaction was not confirmed, and a bare protein binding term conveys no functional specificity. Retain as supporting evidence of a physical interaction but treat as non-core; the core MF terms are the helicase/ATPase activities. Supporting Evidence: PMID:31283754 NMAD-1 directly bound to MTSS-1, TOP-2, and MCM-4, components of the DNA replication machinery PMID:31283754 To test whether these candidate NMAD-1 binding proteins bound directly to NMAD-1, we performed in vitro binding assays using recombinant His-tagged NMAD-1 and GST-tagged or untagged candidate binders
GO:0007399 nervous system development	IMP PMID:7262539 Isolation and genetic characterization of cell-lineage mutan...	KEEP AS NON CORE	Summary: This annotation derives from the classic cell-lineage mutant screen in which lin-6(e1466) (= mcm-4) was isolated. The neuronal/lineage phenotypes are a pleiotropic downstream consequence of a general postembryonic DNA-replication defect in dividing cells, not evidence of a dedicated molecular role of MCM-4 in nervous system development. Reason: lin-6/mcm-4 mutants were recovered as postembryonic cell-lineage mutants; defective DNA replication in dividing neuroblasts secondarily disrupts nervous system development. This is non-core pleiotropy of the core replication defect. The supporting reference (PMID:7262539) is abstract-only in our cache, so the experimental IMP is retained (not removed) but reframed as non-core. Defer to the curator on the underlying assertion. Supporting Evidence: PMID:21146520 The lin-6(e1466) mutation was identified in the first systematic search for mutants with defects in the normally invariant postembryonic cell lineages of C. elegans
GO:0008406 gonad development	IMP PMID:7262539 Isolation and genetic characterization of cell-lineage mutan...	KEEP AS NON CORE	Summary: Like the nervous system annotation, this reflects pleiotropic cell-lineage defects of lin-6/mcm-4 mutants rather than a dedicated gonadal developmental function. The gonad/germline actually copes relatively well with loss of zygotic mcm-4, continuing replication and division into late larval stages. Reason: Gonad development defects are a secondary consequence of impaired postembryonic DNA replication in dividing somatic/germline precursors, not a core function of MCM-4. The IMP source (PMID:7262539) is abstract-only in our cache, so the experimental annotation is retained and reframed as non-core rather than removed. Supporting Evidence: PMID:21146520 the somatic gonad and germline show substantial ability to cope with lack of zygotic mcm-4 function
GO:0040011 locomotion	IMP PMID:7262539 Isolation and genetic characterization of cell-lineage mutan...	KEEP AS NON CORE	Summary: Locomotion defects in lin-6/mcm-4 mutants are again a pleiotropic, whole-organism consequence of impaired postembryonic cell divisions (slow growth, larval arrest/lethality, defective lineages), not evidence that MCM-4 has a specific molecular role in locomotion. Reason: Locomotion is a distal phenotype of the general replication/growth defect caused by loss of mcm-4; it does not represent a core molecular or cellular function. The IMP source (PMID:7262539) is abstract-only in our cache, so the annotation is retained and marked non-core rather than removed. Supporting Evidence: PMID:21146520 These mutants grow slowly and either die during larval development or develop into sterile adults
GO:0005634 nucleus	IDA PMID:21146520 C. elegans MCM-4 is a general DNA replication and checkpoint...	ACCEPT	Summary: Direct experimental evidence localizes MCM-4 to the nucleus / nuclear chromatin in dividing C. elegans cells. This is the experimental basis for the nuclear localization (consistent with the electronic GO:0005634 annotation). Reason: Strong direct evidence; nuclear/chromatin localization is expected and observed for a pre-RC subunit. MCM-4 is nuclear during interphase with a large soluble pool, consistent with regulated licensing. Supporting Evidence: PMID:21146520 The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase file:worm/mcm-4/mcm-4-deep-research-falcon.md MCM-4 is nuclear during interphase, becomes diffuse upon nuclear envelope breakdown and is not associated with metaphase chromatin, and then reassociates with chromatin in late anaphase

Core Functions

MCM-4 is a subunit of the heterohexameric MCM2-7 complex, the core of the eukaryotic replicative DNA helicase, providing ssDNA-translocating helicase activity that unwinds template DNA at replication origins and forks.

Molecular Function:

DNA helicase activity

Directly Involved In:

DNA replication

In Complex:

MCM complex

Supporting Evidence:

PMID:31283754
MCM-4 is a component of the minichromosome maintenance complex which is responsible for licensing origins for DNA replication and is the DNA helicase complex responsible for unwinding the DNA at the origins of replication

Through its conserved MCM AAA+ ATPase module, MCM-4 contributes ATP binding and hydrolysis that powers DNA unwinding by the MCM2-7 ring.

Molecular Function:

ATP hydrolysis activity

In Complex:

MCM complex

Supporting Evidence:

PMID:31283754
is the DNA helicase complex responsible for unwinding the DNA at the origins of replication

MCM-4 is required for licensing of replication origins and initiation of S-phase DNA replication as part of the pre-replication complex, and for bulk DNA synthesis in postembryonic somatic lineages.

Molecular Function:

DNA helicase activity

Directly Involved In:

DNA replication initiation mitotic DNA replication initiation

Supporting Evidence:

PMID:21146520
Our results support a conserved function of mcm-4 in replication licensing, DNA synthesis and the replication checkpoint

MCM-4 is required for the DNA replication checkpoint that couples mitotic entry to completion of S phase; in its absence cells enter mitosis despite incomplete or absent DNA replication.

Directly Involved In:

DNA replication

Supporting Evidence:

PMID:21146520
lin-6 is required for the checkpoint that couples M phase entry to S phase completion

References

GO_REF:0000002

Gene Ontology annotation through association of InterPro records with GO terms

GO_REF:0000024

Manual transfer of experimentally-verified manual GO annotation data to orthologs by curator judgment of sequence similarity

GO_REF:0000033

Annotation inferences using phylogenetic trees

GO_REF:0000044

Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location vocabulary mapping, accompanied by conservative changes to GO terms applied by UniProt

GO_REF:0000116

Automatic Gene Ontology annotation based on Rhea mapping

GO_REF:0000120

Combined Automated Annotation using Multiple IEA Methods

file:worm/mcm-4/mcm-4-deep-research-falcon.md

Deep research report on mcm-4 (falcon/Edison)

MCM-4 contributes as one subunit to the ATPase and helicase activities of the MCM2-7/CMG complex, with ATP hydrolysis in the MCM ring driving DNA translocation and unwinding.

"MCM proteins carry ATP-binding motifs and are attributed ATPase and helicase activities, with ATP hydrolysis within the MCM ring driving DNA translocation and unwinding in CMG."

doi:10.5772/19397

Regulation of DNA synthesis and replication checkpoint activation during C. elegans development.

PMID:21146520

C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability.

lin-6 corresponds to mcm-4, encoding the C. elegans MCM4 ortholog, a conserved subunit of the MCM2-7 pre-RC and replicative helicase complex.

"lin-6 corresponds to mcm-4 and encodes an evolutionarily conserved component of the MCM2-7 pre-RC and replicative helicase complex."
mcm-4 is required for postembryonic somatic DNA synthesis and for the replication checkpoint coupling M-phase entry to S-phase completion.

"lin-6 is required for the checkpoint that couples M phase entry to S phase completion"
MCM-4 is expressed in all dividing cells and associates with chromatin in late anaphase.

"The MCM-4 protein is expressed in all dividing cells during embryonic and postembryonic development and associates with chromatin in late anaphase"

PMID:31283754

The demethylase NMAD-1 regulates DNA replication and repair in the Caenorhabditis elegans germline.

NMAD-1 binds MCM-4 directly in vitro (recombinant pulldown); MCM-4 was identified in NMAD-1 IP/MS as a candidate binder, but the NMAD-1/MCM-4 interaction was not confirmed in vivo (only NMAD-1/TOP-2 was confirmed in vivo).

"NMAD-1 directly bound to MTSS-1, TOP-2, and MCM-4, components of the DNA replication machinery"

PMID:7262539

Isolation and genetic characterization of cell-lineage mutants of the nematode Caenorhabditis elegans.

Classic screen for postembryonic cell-lineage (lin) mutants in which lin-6(e1466), later shown to be mcm-4, was isolated.

"The lin-6(e1466) mutation was identified in the first systematic search for mutants with defects in the normally invariant postembryonic cell lineages of C. elegans"

Suggested Experiments

Experiment: Reconstitute or affinity-purify the C. elegans MCM2-7 / CMG complex and measure ATP-dependent single-stranded DNA helicase and ATPase activity to directly confirm MCM-4 incorporation and biochemical function.

Hypothesis: C. elegans MCM-4 assembles into a functional MCM2-7/CMG complex with ATP-dependent DNA helicase activity, as predicted from orthology.

Experiment: Use tissue-specific degron/auxin-inducible depletion of MCM-4 (germline vs. hypodermis vs. neurons) to dissect lineage-specific replication requirements and separate the primary replication defect from downstream developmental phenotypes.

Hypothesis: The developmental (nervous system, gonad, locomotion) phenotypes are secondary to loss of DNA replication in dividing precursors rather than a tissue-specific molecular function of MCM-4.

Experiment: Map the MCM-4/NMAD-1 interaction interface and test whether NMAD-1 demethylase activity modulates MCM-4 chromatin loading or replication/repair in the germline.

Hypothesis: NMAD-1 regulates MCM-4-dependent replication/repair in the germline through a direct physical interaction.

Deep Research

Falcon

(mcm-4-deep-research-falcon.md)

Research Report: *Caenorhabditis elegans* **mcm-4** (UniProt: Q95XQ8) Falcon Edison Scientific Literature 51 citations 2 artifacts 2026-06-16T17:22:48.242715

Edison artifact artifact-00 (text/markdown)

## Context ID: pqac-00000030 The requested visual content can be found in Figures 5, 6, and 7 of the document. - **Figure 5** shows the expression and localizat (image/png)

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Research Report: Caenorhabditis elegans mcm-4 (UniProt: Q95XQ8)

Executive summary

The C. elegans gene mcm-4 (historically lin-6; UniProt lists additional synonyms including let-358) encodes the MCM4 subunit of the conserved MCM2–7 replicative helicase/replication-licensing machinery, a core component required to license DNA replication origins and (after activation as CMG) unwind DNA during S phase. In worms, loss of mcm-4 uncouples cell-cycle progression from DNA synthesis (mitosis can proceed despite failed replication), reveals roles in replication checkpoint signaling, and shows strong tissue-specific requirements—particularly in the epidermis for organismal growth and viability. Recent 2023–2024 structural and mechanistic work across eukaryotes has clarified how loaded MCM double hexamers are activated into CMG to melt/unwind origins, and 2024 C. elegans genetics provides evidence that the CMG complex can also influence cell-fate divergence via chromatin/histone-inheritance mechanisms, highlighting potential noncanonical functions of MCM-containing assemblies.

1. Identity verification and definitions (critical disambiguation)

1.1 Verified gene/protein identity (worm-specific)

Primary C. elegans genetics explicitly establishes that the historical locus lin-6 corresponds to mcm-4 and encodes the single C. elegans MCM-4 subunit of the MCM2–7 replicative helicase, within the replication pre-initiation/licensing machinery. (korzelius2011c.elegansmcm4 pages 4-5, korzelius2011c.elegansmcm4 pages 9-9, korzelius2011c.elegansmcm4 pages 1-2)

Important scope note. The retrieved primary literature directly supports the mcm-4 ↔ lin-6 ↔ MCM4-ortholog mapping in C. elegans, but it does not explicitly mention the UniProt accession Q95XQ8 or the synonym let-358 in the excerpted sections available here; those identifiers are therefore treated as database-provided context rather than paper-verified in this report. (korzelius2011c.elegansmcm4 pages 2-3, korzelius2011c.elegansmcm4 pages 4-5)

1.2 Key concepts and definitions (current understanding)

Replication licensing: loading of inactive MCM2–7 double hexamers onto origin DNA in G1 (or mitotic exit in rapidly cycling systems) to ensure “once-per-cell-cycle” replication competence. (you2024assemblyactivationand pages 1-2, you2024assemblyactivationand pages 4-6)
MCM2–7: conserved ring-shaped heterohexamer of AAA+ ATPases (MCM2–MCM7) forming the catalytic core of the eukaryotic replicative helicase; loaded as a head-to-head double hexamer during licensing. (you2024assemblyactivationand pages 1-2, henrikus2024unwindingofa pages 1-2)
CMG helicase: the active replicative helicase complex Cdc45–MCM2–7–GINS, formed at origin firing; it drives fork progression by unwinding DNA. (you2024assemblyactivationand pages 4-6, xiang2023thecmghelicase pages 4-6)
Steric-exclusion DNA unwinding: a leading mechanistic model in which CMG encircles one strand (leading-strand template) and excludes the other strand during translocation, generating ssDNA for polymerases. (you2024assemblyactivationand pages 1-2)

2. Molecular function and enzymatic activity of MCM-4 (MCM4)

2.1 What reaction/activity is catalyzed?

MCM-4 is not typically a standalone enzyme; rather, it contributes as one subunit to the enzymatic activities of the MCM2–7/CMG helicase. MCM proteins carry ATP-binding motifs and are attributed ATPase and helicase activities, with ATP hydrolysis within the MCM ring driving DNA translocation and unwinding in CMG. (you2024assemblyactivationand pages 2-4, xiang2023thecmghelicase pages 4-6)

A widely used biochemical dissection highlights that an MCM4/6/7 subcomplex exhibits intrinsic ssDNA-dependent ATP hydrolysis and 3′→5′ helicase activity, with preferences for forked/bubble DNA structures and certain ssDNA contexts (e.g., T-rich ssDNA activating activity). This informs substrate and polarity expectations for MCM4-containing helicase action in vivo. (you2024assemblyactivationand pages 2-4)

2.2 Substrate specificity and directionality

At the replication fork, the activated CMG helicase translocates 3′→5′ on the leading-strand ssDNA template while unwinding parental duplex DNA, thereby providing ssDNA templates for polymerases. (xiang2023thecmghelicase pages 4-6, xu2023synergismbetweencmg pages 1-2)

2.3 Complex membership and mechanistic role of MCM-4

In vivo, the full MCM2–7 heterohexamer is required for replication licensing and for initiation/elongation; activation into CMG occurs via kinase-driven recruitment of firing factors and accessory proteins. (you2024assemblyactivationand pages 1-2, you2024assemblyactivationand pages 4-6)

3. Biological roles and pathways in C. elegans

3.1 Canonical role: DNA replication licensing and S-phase progression

In C. elegans, mcm-4/lin-6 is required for DNA synthesis in multiple somatic lineages; mutants can enter the G1/S transition but fail to replicate DNA in most postembryonic lineages. (korzelius2011c.elegansmcm4 pages 4-5, korzelius2011c.elegansmcm4 pages 1-2)

The cell-cycle timing and localization of MCM-4 support a licensing role: MCM-4 associates with chromatin in late anaphase (a conserved licensing window at mitotic exit) and is strongly induced around S-phase onset in cycling lineages. (korzelius2011c.elegansmcm4 pages 9-11, korzelius2011c.elegansmcm4 pages 9-9)

3.2 Replication checkpoint contributions

Worm experiments support that MCM-4 contributes to replication checkpoint responses: embryos depleted of MCM components can show absence of DNA replication with continued mitotic DNA segregation and genome fragmentation, consistent with defective coupling between replication completion and mitotic entry. (korzelius2011c.elegansmcm4 pages 5-7)

Moreover, MCM-4 perturbation can reduce a replication-stress-induced delay of mitotic progression (e.g., in contexts of nucleotide depletion), consistent with MCM-dependent generation of ssDNA at stalled forks that enables checkpoint signaling (ATR/CHK-1 pathway logic discussed in the worm study). (korzelius2011c.elegansmcm4 pages 5-7, korzelius2011c.elegansmcm4 pages 9-11)

3.3 Tissue-specific requirements (key functional insight)

Despite being a core replication factor, mcm-4 shows a striking tissue-specific requirement for animal growth and viability. Epidermal expression of MCM-4 (Pdpy-7-driven) restores larval growth and viability in mcm-4 mutants, whereas intestine-specific expression rescues intestinal nuclear divisions/endoreduplication but not organismal viability. (korzelius2011c.elegansmcm4 pages 9-9, korzelius2011c.elegansmcm4 pages 9-11)

4. Subcellular localization: where MCM-4 acts in the cell

MCM-4 acts in the nucleus/chromatin compartment consistent with its licensing/helicase roles. In C. elegans, MCM-4 is nuclear during interphase, becomes diffuse upon nuclear envelope breakdown and is not associated with metaphase chromatin, and then reassociates with chromatin in late anaphase, consistent with re-licensing at mitotic exit. (korzelius2011c.elegansmcm4 pages 9-9, ruijtenberg2011regulationofdna pages 3-6, korzelius2011c.elegansmcm4 pages 5-7)

Live-embryo imaging of other MCM2–7 subunits (e.g., GFP–MCM-2/3) demonstrates that chromatin association during late M phase depends on pre-RC factors (CDC-6, CDT-1, ORC) and that nuclear accumulation can include a large soluble pool during interphase. This supports the conserved model that MCM chromatin loading is temporally regulated and tightly controlled to prevent rereplication. (sonneville2012thedynamicsof pages 2-4, sonneville2012thedynamicsof pages 1-2)

Visual support. Key images from Korzelius et al. (2011) show MCM-4 localization dynamics (Figures 5–6) and epidermal rescue (Figure 7). (korzelius2011c.elegansmcm4 media d50caf5d, korzelius2011c.elegansmcm4 media a6161eb6, korzelius2011c.elegansmcm4 media 9b7439f9)

5. Recent developments (prioritizing 2023–2024)

5.1 Mechanistic/structural advances: how origins are unwound and CMG is activated

A 2024 cryo-EM reconstitution study visualized staged origin unwinding: firing factors assemble on the MCM double hexamer to nucleate DNA melting, with quantifiable initial distortion (reported as ~0.7 turns untwisted and ≥3 bp broken in early intermediates), and Mcm10 then triggers splitting into two helicases and lagging-strand ejection to form productive forks. (henrikus2024unwindingofa pages 1-2)

A 2024 review synthesizes biochemical and structural data supporting steric-exclusion unwinding, highlighting kinase regulation (DDK/CDK) and stepwise recruitment of Cdc45/GINS to form active CMG. (you2024assemblyactivationand pages 1-2, you2024assemblyactivationand pages 6-7)

A 2023 Nature Communications structural study further emphasizes ordered kinase-dependent assembly and the coupling between CMG and leading-strand polymerase Polε, describing ATPase-site rearrangements and dynamic polymerase engagement that coordinates unwinding and synthesis. (xu2023synergismbetweencmg pages 1-2)

5.2 New worm biology: replication-independent roles of the CMG complex in fate decisions

A 2024 C. elegans Nature Communications study reports that the CMG helicase complex (studying GINS subunit PSF-2) is required for divergence of daughter fates during asymmetric divisions, including transcriptional upregulation of the pro-apoptotic gene egl-1. The authors propose a mechanism separable from DNA unwinding, implicating replication-coupled chromatin/histone-handling activities (histone chaperone-like effects) that produce epigenetic changes at the egl-1 locus during mother-cell replication. Quantitative results include: the worm soma produces 1090 somatic cells with 131 deaths, apoptosis occurs ~20–30 min after terminal division, and psf-2 perturbation blocks specific programmed deaths (e.g., 67% of MSpaapp deaths blocked) and disrupts egl-1 mRNA asymmetry measured by single-molecule RNA FISH. (memar2024thereplicativehelicase pages 1-2, memar2024thereplicativehelicase pages 8-9)

Although this is not mcm-4-specific, it is highly relevant context because MCM-4 is an obligate CMG core subunit; thus the study motivates careful consideration of potential beyond-replication roles for CMG/MCM assemblies in worm development. (memar2024thereplicativehelicase pages 1-2, memar2024thereplicativehelicase pages 10-11)

5.3 Translational development: CMG/MCM inhibition

A 2024 Molecular Cancer Therapeutics study identified ATP-competitive inhibitors of human CMG/MCM ATPase/helicase activity (amino-coumarins clorobiocin and coumermycin-A1) that disrupt ATP-dependent CMG assembly steps (e.g., MCM ring assembly and GINS recruitment) and destabilize replisome components, inducing DNA damage and selective toxicity in K-Ras mutant tumor cells. This is a concrete example of “real-world implementation” of mechanistic MCM research in drug discovery. (xiang2024identificationofatpcompetitive pages 1-2)

6. Current applications and real-world implementations in worm research

6.1 Live reporters and imaging tools

Worm studies have implemented MCM-4::mCherry reporters (including MosSCI single-copy rescue constructs) to visualize cell-cycle regulated localization and to validate functional rescue of mcm-4 null mutants. (ruijtenberg2011regulationofdna pages 1-3, ruijtenberg2011regulationofdna pages 3-6)

A 2017 PLoS ONE paper developed a live reporter for cell-cycle entry that combines the mcm-4 promoter (as a readout of Rb/E2F-mediated transcriptional control) with a CDK-activity sensor to mark cell-cycle commitment in seam cells—illustrating practical use of mcm-4 regulatory sequences as a proliferation/cell-cycle marker. (xiang2024identificationofatpcompetitive pages 1-2)

6.2 Assays for DNA replication and cell-cycle analysis

Worm replication studies use EdU/BrdU incorporation, DNA-content quantification by confocal serial sections, and flow cytometry of dissociated cells with GFP gating to analyze replication and cell-cycle states in specific tissues. (ruijtenberg2011regulationofdna pages 3-6)

7. Expert synthesis and interpretation

7.1 Why does a “general replication factor” show tissue-specific essentiality?

The C. elegans mcm-4 literature indicates a general replication/helicase role but a particularly strong epidermal requirement for growth/viability (rescuable by epidermal expression). A plausible expert interpretation (consistent with licensing theory) is that tissues differ in replication demand, tolerance to replication stress, reliance on dormant origins, and checkpoint robustness; in such a model, an epidermal lineage could be more sensitive to reduced licensing/helicase capacity. This interpretation aligns with the broader licensing framework where excess loaded MCM supports dormant origins under stress and replication completion. (korzelius2011c.elegansmcm4 pages 9-9, korzelius2011c.elegansmcm4 pages 9-11, you2024assemblyactivationand pages 1-2)

7.2 Noncanonical CMG/MCM functions: an emerging frontier

The 2024 finding that CMG (via GINS subunit PSF-2) can influence fate divergence through a mechanism proposed to be independent of unwinding suggests that MCM-containing replisome components may contribute to chromatin-state inheritance and gene-expression competence. For mcm-4 annotation, the strongest evidence remains canonical licensing/helicase roles, but functional annotation should remain open to CMG-dependent chromatin regulation in specific developmental contexts. (memar2024thereplicativehelicase pages 1-2, memar2024thereplicativehelicase pages 10-11, memar2024thereplicativehelicase pages 8-9)

Evidence summary table

The following table consolidates the main findings, explicitly separating worm primary evidence from cross-species mechanistic inference and listing quantitative datapoints.

Topic	Key findings	Evidence type (worm primary vs cross-species review/structural)	Best supporting sources (authors, year, URL)	Citation IDs to use
Identity / synonyms	The target is Caenorhabditis elegans mcm-4, historically identified as lin-6; primary worm literature states that lin-6 corresponds to mcm-4 and encodes the single C. elegans MCM-4 subunit of the MCM2-7 replicative helicase / replication licensing machinery. UniProt-provided synonyms also include let-358; this synonym was not explicitly recovered in the retrieved papers, so it should be treated as database-supported rather than paper-verified here.	Worm primary + database-context alignment	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009; Ruijtenberg et al., 2011, https://doi.org/10.5772/19397	(korzelius2011c.elegansmcm4 pages 2-3, korzelius2011c.elegansmcm4 pages 4-5, korzelius2011c.elegansmcm4 pages 9-9, ruijtenberg2011regulationofdna pages 3-6)
Molecular function	MCM-4 functions as one subunit of the AAA+ ATPase MCM2-7 heterohexamer, the core of the eukaryotic replicative helicase. In active form, CMG (Cdc45-MCM2-7-GINS) uses ATP hydrolysis to unwind parental duplex DNA by steric exclusion while translocating 3'→5' on the leading-strand ssDNA. Substrate context: dsDNA at licensed origins is converted to ssDNA templates for replication forks; MCM4 contributes to this complex activity rather than acting as a known standalone enzyme in worms.	Cross-species review/structural, used to infer precise biochemistry for worm ortholog	You & Masai, 2024, https://doi.org/10.3390/biology13080629; Xu et al., 2023, https://doi.org/10.1038/s41467-023-41506-0; Xiang et al., 2023, https://doi.org/10.1038/s41388-022-02572-8	(you2024assemblyactivationand pages 2-4, you2024assemblyactivationand pages 1-2, you2024assemblyactivationand pages 4-6, xiang2023thecmghelicase pages 4-6, xu2023synergismbetweencmg pages 1-2)
Biological processes / pathways	Core role in replication licensing, origin firing, S-phase progression, and the replication checkpoint. In worms, mcm-4 is required for productive DNA synthesis and contributes to checkpoint-dependent delay of mitosis under replication stress; it acts in the conserved pathway with ORC, CDC-6, CDT-1, and downstream CMG assembly/activation factors.	Worm primary with mechanistic support from reviews	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009; Sonneville et al., 2012, https://doi.org/10.1083/jcb.201110080; Gaggioli et al., 2014, https://doi.org/10.1083/jcb.201310083; You & Masai, 2024, https://doi.org/10.3390/biology13080629	(korzelius2011c.elegansmcm4 pages 5-7, korzelius2011c.elegansmcm4 pages 9-11, ruijtenberg2011regulationofdna pages 3-6, sonneville2012thedynamicsof pages 2-4, sonneville2012thedynamicsof pages 1-2, sonneville2012thedynamicsof pages 4-6)
Localization / dynamics	In C. elegans, MCM-4 is nuclear during interphase, diffuse / not chromosome-associated in metaphase, and re-associates with chromatin in late anaphase, matching licensing at mitotic exit. Related worm imaging of MCM2-7 shows loading in late M / early G1, with a large soluble nuclear pool in interphase and pre-RC dependence on cdc-6/cdt-1/orc-5.	Worm primary	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009; Sonneville et al., 2012, https://doi.org/10.1083/jcb.201110080; Sonneville et al., 2015, https://doi.org/10.1016/j.celrep.2015.06.046	(sonneville2012thedynamicsof pages 2-4, korzelius2011c.elegansmcm4 pages 9-9, ruijtenberg2011regulationofdna pages 3-6, korzelius2011c.elegansmcm4 pages 5-7, sonneville2015bothchromosomedecondensation pages 1-3, korzelius2011c.elegansmcm4 pages 1-2)
Key phenotypes	Loss of mcm-4 causes failure of DNA replication with continued mitotic chromosome segregation, genome fragmentation, and defective checkpoint responses. Postembryonic somatic lineages are strongly affected, while gonad/germline can continue divisions longer, likely due to maternal product and stronger checkpoint buffering.	Worm primary	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009	(korzelius2011c.elegansmcm4 pages 5-7, korzelius2011c.elegansmcm4 pages 7-9, korzelius2011c.elegansmcm4 pages 4-5, korzelius2011c.elegansmcm4 pages 1-2)
Tissue-specific requirements	Although mcm-4 has a general replication role, worm experiments show an epidermis-specific requirement for organismal growth and viability. Pdpy-7::MCM-4::mCherry rescues larval growth and viability, while intestine-specific expression rescues intestinal nuclear divisions/endoreduplication but not whole-animal viability. This indicates strong tissue-specific sensitivity despite conserved core function.	Worm primary	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009	(korzelius2011c.elegansmcm4 pages 9-9, korzelius2011c.elegansmcm4 pages 9-11)
Replication-independent / beyond-replication roles	Recent C. elegans work on CMG, though centered on PSF-2/GINS2 rather than mcm-4 directly, shows that the replicative helicase can influence asymmetric cell-fate divergence and egl-1 transcription through a proposed histone-chaperone / chromatin inheritance mechanism that is separable from bulk DNA unwinding. This is relevant for interpreting potential noncanonical roles of MCM4-containing CMG in worms.	Worm primary (complex-level inference, not mcm-4-specific)	Memar et al., 2024, https://doi.org/10.1038/s41467-024-53715-2; Rankin & Rankin, 2024, https://doi.org/10.3390/biology13040258	(memar2024thereplicativehelicase pages 1-2, memar2024thereplicativehelicase pages 11-12, memar2024thereplicativehelicase pages 10-11, memar2024thereplicativehelicase pages 9-10, memar2024thereplicativehelicase pages 8-9)
Recent structural/mechanistic developments (2023-2024)	2023-2024 studies sharpen the mechanism of MCM activation: loaded double hexamers are converted into active CMG by DDK/CDK-dependent phosphorylation, recruitment of Cdc45/GINS/Polε, and Mcm10-triggered helicase splitting/origin melting. Cryo-EM visualized local origin unwinding, including ~0.7 turns untwisted and ≥3 bp broken in early activation intermediates.	Cross-species primary structural + review	Henrikus et al., 2024, https://doi.org/10.1038/s41594-024-01280-z; You & Masai, 2024, https://doi.org/10.3390/biology13080629; Weissmann et al., 2024, https://doi.org/10.1038/s41586-024-08263-6	(you2024assemblyactivationand pages 1-2, henrikus2024unwindingofa pages 1-2, you2024assemblyactivationand pages 6-7)
Applications / real-world implementations	In worms, MCM-4 promoter/reporters are used as practical cell-cycle entry and proliferation markers; live MCM-4::mCherry supports lineage-level imaging of licensing dynamics. More broadly, the CMG/MCM ATPase has become a tractable intervention point: 2024 work identified ATP-competitive CMG/MCM inhibitors (e.g., clorobiocin, coumermycin-A1) that disrupt helicase assembly and fork function, illustrating translational relevance of the MCM4-containing complex.	Worm tool + cross-species therapeutic application	van Rijnberk et al., 2017, https://doi.org/10.1371/journal.pone.0171600; Ruijtenberg et al., 2011, https://doi.org/10.5772/19397; Xiang et al., 2024, https://doi.org/10.1158/1535-7163.mct-23-0904	(ruijtenberg2011regulationofdna pages 3-6, xiang2024identificationofatpcompetitive pages 1-2)
Key quantitative / statistical data points	MCM-4 protein predicted at 823 aa in C. elegans. In structural activation intermediates, origin DNA is untwisted by ~0.7 turns with at least 3 bp broken. In the 2024 CMG fate-divergence study, the C. elegans soma produces 1090 somatic cells, 131 die, and apoptosis occurs ~20–30 min after terminal division; in psf-2(t3443ts), 67% of MSpaapp deaths were blocked and AMso fate defects reached 82% (167/204) among divisions scored.	Mixed: worm primary + cross-species structural + worm primary beyond-replication	Korzelius et al., 2011, https://doi.org/10.1016/j.ydbio.2010.12.009; Henrikus et al., 2024, https://doi.org/10.1038/s41594-024-01280-z; Memar et al., 2024, https://doi.org/10.1038/s41467-024-53715-2	(korzelius2011c.elegansmcm4 pages 2-3, henrikus2024unwindingofa pages 1-2, memar2024thereplicativehelicase pages 1-2, memar2024thereplicativehelicase pages 9-10, memar2024thereplicativehelicase pages 8-9)

Table: This table condenses the most relevant identity, function, localization, phenotype, and recent mechanistic findings for C. elegans mcm-4/lin-6. It separates direct worm evidence from cross-species mechanistic inference and provides citation IDs for efficient reuse in the final report.

References (URLs and publication dates)

Korzelius J. et al. “C. elegans MCM-4 is a general DNA replication and checkpoint component with an epidermis-specific requirement for growth and viability.” Developmental Biology (Feb 2011). https://doi.org/10.1016/j.ydbio.2010.12.009 (korzelius2011c.elegansmcm4 pages 1-2)
Sonneville R. et al. “The dynamics of replication licensing in live Caenorhabditis elegans embryos.” J Cell Biol (Jan 2012). https://doi.org/10.1083/jcb.201110080 (sonneville2012thedynamicsof pages 1-2)
Sonneville R. et al. “Both Chromosome Decondensation and Condensation Are Dependent on DNA Replication in C. elegans Embryos.” Cell Reports (Jul 2015). https://doi.org/10.1016/j.celrep.2015.06.046 (sonneville2015bothchromosomedecondensation pages 1-3)
You Z, Masai H. “Assembly, Activation, and Helicase Actions of MCM2-7…” Biology (Aug 2024). https://doi.org/10.3390/biology13080629 (you2024assemblyactivationand pages 1-2)
Henrikus S.S. et al. “Unwinding of a eukaryotic origin of replication visualized by cryo-EM.” Nat Struct Mol Biol (May 2024). https://doi.org/10.1038/s41594-024-01280-z (henrikus2024unwindingofa pages 1-2)
Xu Z. et al. “Synergism between CMG helicase and leading strand DNA polymerase at replication fork.” Nat Communications (Sep 2023). https://doi.org/10.1038/s41467-023-41506-0 (xu2023synergismbetweencmg pages 1-2)
Xiang S. et al. “The CMG helicase and cancer…” Oncogene (Dec 2023). https://doi.org/10.1038/s41388-022-02572-8 (xiang2023thecmghelicase pages 4-6)
Memar N. et al. “The replicative helicase CMG is required for the divergence of cell fates during asymmetric cell division in vivo.” Nat Communications (Oct 2024). https://doi.org/10.1038/s41467-024-53715-2 (memar2024thereplicativehelicase pages 1-2)
Xiang S. et al. “Identification of ATP-Competitive Human CMG Helicase Inhibitors…” Molecular Cancer Therapeutics (Jul 2024). https://doi.org/10.1158/1535-7163.mct-23-0904 (xiang2024identificationofatpcompetitive pages 1-2)
van Rijnberk L.M. et al. “A dual transcriptional reporter and CDK-activity sensor marks cell cycle entry and progression in C. elegans.” PLOS ONE (Feb 2017). https://doi.org/10.1371/journal.pone.0171600 (xiang2024identificationofatpcompetitive pages 1-2)

References

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(korzelius2011c.elegansmcm4 pages 9-9): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(korzelius2011c.elegansmcm4 pages 1-2): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(korzelius2011c.elegansmcm4 pages 2-3): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
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(korzelius2011c.elegansmcm4 pages 9-11): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(korzelius2011c.elegansmcm4 pages 5-7): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
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(sonneville2012thedynamicsof pages 1-2): Remi Sonneville, Matthieu Querenet, Ashley Craig, Anton Gartner, and J. Julian Blow. The dynamics of replication licensing in live caenorhabditis elegans embryos. The Journal of Cell Biology, 196:233-246, Jan 2012. URL: https://doi.org/10.1083/jcb.201110080, doi:10.1083/jcb.201110080. This article has 88 citations.
(korzelius2011c.elegansmcm4 media d50caf5d): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(korzelius2011c.elegansmcm4 media a6161eb6): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(korzelius2011c.elegansmcm4 media 9b7439f9): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(you2024assemblyactivationand pages 6-7): Zhiying You and Hisao Masai. Assembly, activation, and helicase actions of mcm2-7: transition from inactive mcm2-7 double hexamers to active replication forks. Biology, 13:629, Aug 2024. URL: https://doi.org/10.3390/biology13080629, doi:10.3390/biology13080629. This article has 9 citations.
(memar2024thereplicativehelicase pages 1-2): Nadin Memar, Ryan Sherrard, Aditya Sethi, Carla Lloret Fernandez, Henning Schmidt, Eric J. Lambie, Richard J. Poole, Ralf Schnabel, and Barbara Conradt. The replicative helicase cmg is required for the divergence of cell fates during asymmetric cell division in vivo. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-53715-2, doi:10.1038/s41467-024-53715-2. This article has 7 citations and is from a highest quality peer-reviewed journal.
(memar2024thereplicativehelicase pages 8-9): Nadin Memar, Ryan Sherrard, Aditya Sethi, Carla Lloret Fernandez, Henning Schmidt, Eric J. Lambie, Richard J. Poole, Ralf Schnabel, and Barbara Conradt. The replicative helicase cmg is required for the divergence of cell fates during asymmetric cell division in vivo. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-53715-2, doi:10.1038/s41467-024-53715-2. This article has 7 citations and is from a highest quality peer-reviewed journal.
(memar2024thereplicativehelicase pages 10-11): Nadin Memar, Ryan Sherrard, Aditya Sethi, Carla Lloret Fernandez, Henning Schmidt, Eric J. Lambie, Richard J. Poole, Ralf Schnabel, and Barbara Conradt. The replicative helicase cmg is required for the divergence of cell fates during asymmetric cell division in vivo. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-53715-2, doi:10.1038/s41467-024-53715-2. This article has 7 citations and is from a highest quality peer-reviewed journal.
(xiang2024identificationofatpcompetitive pages 1-2): Shengyan Xiang, Kendall C. Craig, Xingju Luo, Darcy L. Welch, Renan B. Ferreira, Harshani R. Lawrence, Nicholas J. Lawrence, Damon R. Reed, and Mark G. Alexandrow. Identification of atp-competitive human cmg helicase inhibitors for cancer intervention that disrupt cmg-replisome function. Molecular Cancer Therapeutics, 23:1568-1585, Jul 2024. URL: https://doi.org/10.1158/1535-7163.mct-23-0904, doi:10.1158/1535-7163.mct-23-0904. This article has 8 citations and is from a peer-reviewed journal.
(ruijtenberg2011regulationofdna pages 1-3): Suzan Ruijtenberg, Sander van den Heuvel, and Inge The. Regulation of dna synthesis and replication checkpoint activation during c. elegans development. ArXiv, Sep 2011. URL: https://doi.org/10.5772/19397, doi:10.5772/19397. This article has 1 citations.
(sonneville2012thedynamicsof pages 4-6): Remi Sonneville, Matthieu Querenet, Ashley Craig, Anton Gartner, and J. Julian Blow. The dynamics of replication licensing in live caenorhabditis elegans embryos. The Journal of Cell Biology, 196:233-246, Jan 2012. URL: https://doi.org/10.1083/jcb.201110080, doi:10.1083/jcb.201110080. This article has 88 citations.
(sonneville2015bothchromosomedecondensation pages 1-3): Remi Sonneville, Gillian Craig, Karim Labib, Anton Gartner, and J. Julian Blow. Both chromosome decondensation and condensation are dependent on dna replication in c. elegans embryos. Cell Reports, 12:405-417, Jul 2015. URL: https://doi.org/10.1016/j.celrep.2015.06.046, doi:10.1016/j.celrep.2015.06.046. This article has 44 citations and is from a highest quality peer-reviewed journal.
(korzelius2011c.elegansmcm4 pages 7-9): Jerome Korzelius, Inge The, Suzan Ruijtenberg, Vincent Portegijs, Huihong Xu, H. Robert Horvitz, and Sander van den Heuvel. C. elegans mcm-4 is a general dna replication and checkpoint component with an epidermis-specific requirement for growth and viability. Developmental Biology, 350:358-369, Feb 2011. URL: https://doi.org/10.1016/j.ydbio.2010.12.009, doi:10.1016/j.ydbio.2010.12.009. This article has 32 citations and is from a peer-reviewed journal.
(memar2024thereplicativehelicase pages 11-12): Nadin Memar, Ryan Sherrard, Aditya Sethi, Carla Lloret Fernandez, Henning Schmidt, Eric J. Lambie, Richard J. Poole, Ralf Schnabel, and Barbara Conradt. The replicative helicase cmg is required for the divergence of cell fates during asymmetric cell division in vivo. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-53715-2, doi:10.1038/s41467-024-53715-2. This article has 7 citations and is from a highest quality peer-reviewed journal.
(memar2024thereplicativehelicase pages 9-10): Nadin Memar, Ryan Sherrard, Aditya Sethi, Carla Lloret Fernandez, Henning Schmidt, Eric J. Lambie, Richard J. Poole, Ralf Schnabel, and Barbara Conradt. The replicative helicase cmg is required for the divergence of cell fates during asymmetric cell division in vivo. Nature Communications, Oct 2024. URL: https://doi.org/10.1038/s41467-024-53715-2, doi:10.1038/s41467-024-53715-2. This article has 7 citations and is from a highest quality peer-reviewed journal.

Artifacts

Edison artifact artifact-00

Citations

you2024assemblyactivationand pages 1-2
you2024assemblyactivationand pages 2-4
henrikus2024unwindingofa pages 1-2
xu2023synergismbetweencmg pages 1-2
xiang2024identificationofatpcompetitive pages 1-2
ruijtenberg2011regulationofdna pages 3-6
sonneville2012thedynamicsof pages 1-2
sonneville2015bothchromosomedecondensation pages 1-3
xiang2023thecmghelicase pages 4-6
memar2024thereplicativehelicase pages 1-2
you2024assemblyactivationand pages 4-6
sonneville2012thedynamicsof pages 2-4
you2024assemblyactivationand pages 6-7
memar2024thereplicativehelicase pages 8-9
memar2024thereplicativehelicase pages 10-11
ruijtenberg2011regulationofdna pages 1-3
sonneville2012thedynamicsof pages 4-6
memar2024thereplicativehelicase pages 11-12
memar2024thereplicativehelicase pages 9-10
https://doi.org/10.1016/j.ydbio.2010.12.009;
https://doi.org/10.5772/19397
https://doi.org/10.3390/biology13080629;
https://doi.org/10.1038/s41467-023-41506-0;
https://doi.org/10.1038/s41388-022-02572-8
https://doi.org/10.1083/jcb.201110080;
https://doi.org/10.1083/jcb.201310083;
https://doi.org/10.3390/biology13080629
https://doi.org/10.1016/j.celrep.2015.06.046
https://doi.org/10.1016/j.ydbio.2010.12.009
https://doi.org/10.1038/s41467-024-53715-2;
https://doi.org/10.3390/biology13040258
https://doi.org/10.1038/s41594-024-01280-z;
https://doi.org/10.1038/s41586-024-08263-6
https://doi.org/10.1371/journal.pone.0171600;
https://doi.org/10.5772/19397;
https://doi.org/10.1158/1535-7163.mct-23-0904
https://doi.org/10.1038/s41467-024-53715-2
https://doi.org/10.1083/jcb.201110080
https://doi.org/10.1038/s41594-024-01280-z
https://doi.org/10.1038/s41467-023-41506-0
https://doi.org/10.1371/journal.pone.0171600
https://doi.org/10.1016/j.ydbio.2010.12.009,
https://doi.org/10.3390/biology13080629,
https://doi.org/10.1038/s41594-024-01280-z,
https://doi.org/10.1038/s41388-022-02572-8,
https://doi.org/10.1038/s41467-023-41506-0,
https://doi.org/10.5772/19397,
https://doi.org/10.1083/jcb.201110080,
https://doi.org/10.1038/s41467-024-53715-2,
https://doi.org/10.1158/1535-7163.mct-23-0904,
https://doi.org/10.1016/j.celrep.2015.06.046,

📚 Additional Documentation

Notes

(mcm-4-notes.md)

mcm-4 (C. elegans) review notes

Identity

UniProt: Q95XQ8 (MCM4_CAEEL), 823 aa
Gene: mcm-4; synonyms let-358, lin-6; ORF Y39G10AR.14
WormBase locus; member of MCM2-7 family (PANTHER PTHR11630, "DNA REPLICATION LICENSING FACTOR MCM FAMILY MEMBER")
Taxon: NCBITaxon:6239

Core function (well established)

mcm-4 encodes the C. elegans ortholog of MCM4, a subunit of the heterohexameric
MCM2-7 pre-replication complex / replicative helicase. As part of the CMG
(CDC45–MCM–GINS) helicase it unwinds template DNA during S-phase. Conserved
roles: replication licensing, DNA synthesis (elongation), and the DNA replication
checkpoint coupling M-phase entry to S-phase completion.

Key evidence from cached publications

PMID:21146520 (Korzelius et al., 2011, Dev Biol) — full text available, PRIMARY

Cloned lin-6 and showed lin-6 = mcm-4, encoding the C. elegans MCM4 ortholog,
member of the MCM2-7 pre-RC / replicative helicase complex.
PMID:21146520
lin-6/mcm-4 mutants lack DNA synthesis in postembryonic somatic lineages while
entry into mitosis continues → checkpoint defect (M phase entry uncoupled from
S phase completion). PMID:21146520
MCM-4 protein expressed in all dividing cells during embryonic and postembryonic
development; associates with chromatin in late anaphase. → supports nucleus /
chromosome / chromatin localization. PMID:21146520
Tissue-specific: epidermis (hypodermis) expression sufficient to rescue growth
retardation/lethality; somatic gonad and germline cope with loss of zygotic mcm-4.
Supports GO: MCM complex, DNA replication, replication initiation, DNA strand
elongation, replication checkpoint, nucleus, chromosome.
EXP located_in chromosome and IDA located_in nucleus both trace to this paper.
NAS premeiotic DNA replication, NAS MCM complex also from this paper (likely
curator narrative statements).

PMID:31283754 (Wang et al., 2019, PLoS Genet) — full text available, PRIMARY

NMAD-1 (DNA demethylase) study. NMAD-1 physically interacts with MCM-4 (and
TOP-2), components of the DNA replication machinery.
PMID:31283754
Source of IPI "protein binding" (GO:0005515) annotation. Real interaction but
"protein binding" is uninformative per curation guidelines.

PMID:7262539 (Sulston & Horvitz, 1981, Genetics) — ABSTRACT ONLY (no full text)

Classic "Isolation and genetic characterization of cell-lineage mutants of the
nematode C. elegans" — the original lin mutant screen where lin-6(e1466) was
isolated. [confirmed via PMID:21146520 "first systematic search for mutants with defects in the normally invariant postembryonic cell lineages... (Sulston and Horvitz, 1981)"]
This is the basis for the IMP annotations to nervous system development
(GO:0007399), gonad development (GO:0008406), locomotion (GO:0040011).
These are pleiotropic downstream phenotypes of a general postembryonic DNA
replication defect in dividing cells — NOT evidence that mcm-4 has a dedicated
developmental/neuronal/locomotor molecular role. Candidate for
KEEP_AS_NON_CORE / MARK_AS_OVER_ANNOTATED. Cannot read full text (abstract only),
so retain rather than REMOVE — defer to curator on the IMP, but mark non-core.

Annotation triage summary (pre-agent)

MF: DNA helicase activity (GO:0003678), single-stranded DNA helicase activity
(GO:0017116, contributes_to), ssDNA binding (GO:0003697), DNA binding
(GO:0003677), ATP binding (GO:0005524), ATP hydrolysis (GO:0016887) → core,
consistent with MCM subunit acting within the hexamer.
CC: MCM complex (GO:0042555), nucleus (GO:0005634), chromosome (GO:0005694) → core.
BP: DNA replication, replication initiation, mitotic DNA replication initiation,
DNA strand elongation, premeiotic DNA replication, BIR (GO:0000727) → replication
processes; some IBA-propagated may be over-specific (e.g. BIR).
BP developmental (nervous system, gonad, locomotion) → non-core pleiotropy.
protein binding (IPI) → uninformative; NMAD-1 interaction is real.

Deep research status

Falcon deep research (just deep-research-falcon worm mcm-4 --fallback perplexity-lite)
was launched in parallel with publication caching. The wrapper reported a 600s timeout
(and the perplexity-lite fallback was unavailable in this environment), but falcon in
fact completed after ~1406s and wrote mcm-4-deep-research-falcon.md (51 citations) plus
artifacts. The report corroborates the entire review: it confirms the
lin-6/let-358 = mcm-4 = MCM4 identity, the complex-level ATPase/helicase activities
(incl. the MCM4/6/7 subcomplex biochemistry), the replication checkpoint role, the
epidermis-specific requirement, and the nuclear→diffuse(NEBD)→late-anaphase chromatin
localization dynamics. No annotation decision needed changing.

New context (not annotation-changing): a 2024 study (Memar et al., Nat Commun) reports a
replication-independent role for the CMG helicase in asymmetric cell-fate divergence
(via the GINS subunit PSF-2, not mcm-4 directly), proposed to act through
chromatin/histone handling at the egl-1 locus. Captured as a new suggested_question and
noted in the deep-research reference_review; MCM-4's strongest evidence remains canonical
licensing/helicase. The deep-research file is now cited (additional_reference_ids +
supported_by) on the ssDNA helicase activity annotation.

Thorough integration pass (follow-up)

Wove the deep-research findings into the relevant annotations beyond the single
ssDNA-helicase citation:
- DNA helicase activity (GO:0003678, IEA) and ATP hydrolysis (GO:0016887, IEA): added
the MCM4/6/7 subcomplex biochemistry (intrinsic ssDNA-dependent ATP hydrolysis;
ATPase/helicase with ATP hydrolysis in the MCM ring driving translocation/unwinding).
- nucleus (GO:0005634, IDA) and chromosome (GO:0005694, EXP): added the cell-cycle
localization dynamics (nuclear interphase → diffuse at NEBD → not on metaphase
chromatin → reassociates in late anaphase).
- Added Ruijtenberg, van den Heuvel & The 2011 (doi:10.5772/19397) to references,
surfaced by deep research; marked correctness=UNVERIFIED because it has no PMID, is
not in the GOA, and was not independently retrieved/read in this review.
All deep-research supporting_text quotes validate against the cached report.

PR #1514 review fix: protein binding (GO:0005515, IPI)

Reviewer correctly flagged that the original supporting_text quoted the NMAD-1/TOP-2
in vivo co-IP and the summary wrongly implied MCM-4 co-IP. Verified from PMID:31283754
full text:
- MCM-4 identified in NMAD-1 IP/MS as a candidate binder.
- NMAD-1 binds MCM-4 directly in vitro (recombinant His-NMAD-1 pulldown of MCM-4;
Fig 4B / S5). PMID:31283754
- In vivo interaction with MCM-4 was not confirmed; only NMAD-1/TOP-2 confirmed in
vivo. PMID:31283754
Corrected the annotation summary/reason and supporting_text accordingly (in vitro direct
binding cited; in vivo caveat stated), and refined the PMID:31283754 reference finding.
Action remains KEEP_AS_NON_CORE (uninformative MF term; in vitro direct binding still
supports the IPI).

📄 View Raw YAML

id: Q95XQ8
gene_symbol: mcm-4
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:6239
  label: Caenorhabditis elegans
description: MCM-4 is the Caenorhabditis elegans ortholog of MCM4, a subunit of
  the heterohexameric MCM2-7 complex that functions as the core of the eukaryotic
  replicative DNA helicase. As part of the pre-replication complex (pre-RC), MCM2-7
  is loaded onto replication origins during late mitosis and G1 to license them for
  replication; at the onset of S phase it is activated and, together with CDC45 and
  the GINS complex, forms the CMG helicase that unwinds template DNA at replication
  forks. The protein contains a conserved MCM AAA+ ATPase module, and the six
  ATPase active sites of the ring are built in trans from interfaces of neighboring
  subunits, so helicase and ATPase activities are properties of the assembled
  complex rather than any single subunit. In C. elegans, mcm-4 (also known as lin-6
  and let-358) is required for postembryonic somatic DNA synthesis and for the
  replication checkpoint that couples mitotic entry to completion of S phase. The
  protein is expressed in all dividing cells during embryonic and postembryonic
  development and associates with chromatin in late anaphase. Loss of mcm-4 blocks
  DNA replication in postembryonic somatic lineages while mitosis still initiates,
  causing pleiotropic cell-lineage defects; expression of MCM-4 in the epidermis
  (hypodermis) is sufficient to rescue the associated growth retardation and
  lethality.
existing_annotations:
- term:
    id: GO:0042555
    label: MCM complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: MCM-4 is a subunit of the heterohexameric MCM2-7 (MCM) complex. This
      is the defining cellular component for the protein and is strongly supported
      phylogenetically (the IBA is propagated across MCM2-7 orthologs from yeast to
      mammals) and by direct C. elegans evidence.
    action: ACCEPT
    reason: Core, well-established localization. MCM-4 is an integral subunit of the
      MCM2-7 pre-RC / replicative helicase complex, supported by orthology and by
      direct study in C. elegans.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: lin-6 corresponds to mcm-4 and encodes an evolutionarily
          conserved component of the MCM2-7 pre-RC and replicative helicase complex.
- term:
    id: GO:0003697
    label: single-stranded DNA binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: As a subunit of the MCM2-7 replicative helicase, MCM-4 contributes to
      binding and translocation along single-stranded DNA during origin unwinding
      and fork progression. ssDNA binding is a conserved property of the MCM ring.
    action: ACCEPT
    reason: Conserved molecular function of MCM subunits within the helicase ring;
      consistent with the replicative helicase role established for C. elegans
      MCM-4. The activity is a property of the assembled complex, but the enables
      qualifier at the subunit level reflects standard MCM annotation practice.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: encodes an evolutionarily conserved component of the MCM2-7
          pre-RC and replicative helicase complex
- term:
    id: GO:0017116
    label: single-stranded DNA helicase activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: contributes_to
  review:
    summary: MCM-4 contributes to the ssDNA-translocating helicase activity of the
      MCM2-7 / CMG complex that unwinds template DNA at replication forks. The
      contributes_to qualifier correctly reflects that helicase activity is a
      property of the assembled hexamer, not the isolated subunit.
    action: ACCEPT
    reason: Conserved replicative helicase function, supported by orthology and by
      the C. elegans demonstration that MCM-4 is a component of the replicative
      helicase complex. The contributes_to qualifier is appropriate for a single
      MCM subunit.
    additional_reference_ids:
      - file:worm/mcm-4/mcm-4-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
      - reference_id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
        supporting_text: MCM proteins carry ATP-binding motifs and are attributed
          ATPase and helicase activities, with ATP hydrolysis within the MCM ring
          driving DNA translocation and unwinding in CMG.
- term:
    id: GO:0006271
    label: DNA strand elongation involved in DNA replication
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: The MCM2-7/CMG helicase unwinds DNA ahead of the replication fork
      during elongation, and MCM-4 is required for DNA synthesis in C. elegans
      somatic lineages. This process annotation is consistent with the replicative
      helicase role.
    action: ACCEPT
    reason: Strand elongation requires continued fork unwinding by the MCM2-7
      helicase; well supported by orthology and by the requirement of mcm-4 for
      postembryonic DNA synthesis.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: C. elegans lin-6 mutants lack DNA synthesis in postembryonic
          somatic cell lineages, while entry into mitosis continues
- term:
    id: GO:1902975
    label: mitotic DNA replication initiation
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: MCM2-7 licensing of origins is the central event in initiation of
      mitotic (S-phase) DNA replication, and MCM-4 is required for this process. The
      term captures the licensing/initiation role of the complex in the mitotic cell
      cycle.
    action: ACCEPT
    reason: Replication licensing by MCM2-7 is required for initiation of mitotic
      DNA replication; supported by orthology and by the C. elegans replication
      defect on loss of mcm-4.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: Our results support a conserved function of mcm-4 in
          replication licensing, DNA synthesis and the replication checkpoint
- term:
    id: GO:0000727
    label: double-strand break repair via break-induced replication
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: involved_in
  review:
    summary: This IBA propagates a break-induced replication (BIR) role across the
      MCM family. BIR uses the replicative helicase to copy DNA from a broken end,
      so MCM involvement is mechanistically plausible, but there is no direct C.
      elegans evidence that MCM-4 functions specifically in BIR, and this is a
      narrow, specialized repair pathway relative to the core replication role.
    action: MARK_AS_OVER_ANNOTATED
    reason: BIR is a specialized DNA double-strand break repair pathway; while the
      replicative helicase can be co-opted for BIR, this phylogenetically-propagated
      term over-specifies the role of MCM-4 in C. elegans, where the documented
      functions are bulk DNA replication and the replication checkpoint. No
      organism-specific evidence supports a dedicated BIR function. Retain as a
      recognized but non-core/over-annotated process rather than a core function.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: Our results support a conserved function of mcm-4 in
          replication licensing, DNA synthesis and the replication checkpoint
- term:
    id: GO:0003677
    label: DNA binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: MCM-4 binds DNA as part of the MCM2-7 helicase ring that encircles and
      translocates along DNA. This InterPro2GO electronic annotation is broad but
      correct.
    action: ACCEPT
    reason: DNA binding is a general, correct parent term for the MCM helicase. The
      more specific single-stranded DNA binding annotation is also present; the
      broader IEA is acceptable.
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: MCM-4 is a component of the minichromosome maintenance
          complex which is responsible for licensing origins for DNA replication
- term:
    id: GO:0003678
    label: DNA helicase activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000120
  qualifier: enables
  review:
    summary: MCM-4 is part of the MCM2-7/CMG replicative DNA helicase. This is a
      core molecular function, correctly captured by this electronic annotation
      (and mirrored by ISS and IBA annotations to the more specific ssDNA helicase
      term).
    action: ACCEPT
    reason: Correct core function for an MCM subunit; the activity is a property of
      the assembled complex but DNA helicase activity is the standard MF annotation
      for MCM proteins.
    additional_reference_ids:
      - file:worm/mcm-4/mcm-4-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
      - reference_id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
        supporting_text: an MCM4/6/7 subcomplex exhibits intrinsic ssDNA-dependent
          ATP hydrolysis
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: MCM-4 contains a conserved MCM AAA+ ATPase module (Walker A/B motifs)
      that binds ATP; ATP binding and hydrolysis power the MCM2-7 helicase. The
      UniProt record annotates EC 3.6.4.12 ATP-dependent DNA helicase activity by
      similarity. This electronic annotation is correct.
    action: ACCEPT
    reason: Direct consequence of the conserved AAA+ ATPase domain; ATP binding is
      a standard, well-supported molecular function for MCM subunits.
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: MCM-4 acts on nuclear chromatin during DNA replication and is detected
      in the nucleus / on chromatin in dividing cells. Nuclear localization is
      consistent with its function and is also directly supported (IDA).
    action: ACCEPT
    reason: Correct subcellular localization, corroborated by direct C. elegans
      evidence (IDA, PMID:21146520) showing chromatin/nuclear association in
      dividing cells.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: The MCM-4 protein is expressed in all dividing cells during
          embryonic and postembryonic development and associates with chromatin in
          late anaphase
- term:
    id: GO:0005694
    label: chromosome
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: MCM-4 associates with chromatin/chromosomes as part of the pre-RC and
      replisome. This electronic annotation is corroborated by direct experimental
      evidence of chromatin association in late anaphase.
    action: ACCEPT
    reason: Correct localization; MCM2-7 is loaded onto origins on chromosomes and
      MCM-4 is observed associating with chromatin (EXP/IDA, PMID:21146520).
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: associates with chromatin in late anaphase
- term:
    id: GO:0006260
    label: DNA replication
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: A core biological process for MCM-4, which is required for DNA
      replication as a subunit of the replicative helicase. Directly supported by
      the C. elegans loss-of-function replication defect.
    action: ACCEPT
    reason: Central, well-established function; mcm-4 mutants fail postembryonic DNA
      synthesis.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: lin-6 mutants lack DNA synthesis in postembryonic somatic
          cell lineages
- term:
    id: GO:0006270
    label: DNA replication initiation
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: involved_in
  review:
    summary: MCM2-7 licensing/loading at origins is required for replication
      initiation, and MCM-4 is part of this process. Consistent with the conserved
      licensing role demonstrated for C. elegans mcm-4.
    action: ACCEPT
    reason: Correct process annotation for an MCM subunit acting in origin licensing
      and initiation.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: Our results support a conserved function of mcm-4 in
          replication licensing, DNA synthesis and the replication checkpoint
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000116
  qualifier: enables
  review:
    summary: The MCM AAA+ module hydrolyzes ATP to drive DNA translocation/unwinding
      by the MCM2-7 ring. This Rhea-mapped electronic annotation is correct; ATP
      hydrolysis powers the replicative helicase.
    action: ACCEPT
    reason: Direct consequence of the conserved ATPase domain; ATP hydrolysis powers
      the MCM2-7/CMG helicase that unwinds origin DNA.
    additional_reference_ids:
      - file:worm/mcm-4/mcm-4-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
      - reference_id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
        supporting_text: MCM proteins carry ATP-binding motifs and are attributed
          ATPase and helicase activities, with ATP hydrolysis within the MCM ring
          driving DNA translocation and unwinding in CMG.
- term:
    id: GO:0042555
    label: MCM complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: part_of
  review:
    summary: Electronic (InterPro2GO) annotation to the MCM complex, duplicating the
      well-supported IBA/NAS/ISS annotations to the same component. Correct.
    action: ACCEPT
    reason: Correct core localization; redundant with the experimentally and
      phylogenetically supported MCM complex annotations.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: encodes an evolutionarily conserved component of the MCM2-7
          pre-RC and replicative helicase complex
- term:
    id: GO:0005694
    label: chromosome
  evidence_type: EXP
  original_reference_id: PMID:21146520
  qualifier: located_in
  review:
    summary: Direct experimental evidence that MCM-4 associates with chromatin
      (chromosomes) in dividing C. elegans cells, observed in late anaphase. This
      is the experimental basis for the chromosome localization.
    action: ACCEPT
    reason: Strong direct evidence from the primary functional paper; MCM-4 is
      chromatin/chromosome-associated as expected for a pre-RC subunit. The cell-cycle
      dynamics (chromatin-associated only at specific cell-cycle windows) are
      consistent with regulated MCM loading.
    additional_reference_ids:
      - file:worm/mcm-4/mcm-4-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: The MCM-4 protein is expressed in all dividing cells during
          embryonic and postembryonic development and associates with chromatin in
          late anaphase
      - reference_id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
        supporting_text: MCM-4 is nuclear during interphase, becomes diffuse upon
          nuclear envelope breakdown and is not associated with metaphase chromatin,
          and then reassociates with chromatin in late anaphase
- term:
    id: GO:0016887
    label: ATP hydrolysis activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: enables
  review:
    summary: ATP hydrolysis activity inferred from sequence/structural similarity to
      MCM4 orthologs bearing the conserved AAA+ ATPase module. Consistent with the
      Rhea-mapped IEA annotation to the same term.
    action: ACCEPT
    reason: Correct; the conserved MCM ATPase domain supports ATP hydrolysis as part
      of the helicase mechanism.
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
- term:
    id: GO:0006279
    label: premeiotic DNA replication
  evidence_type: NAS
  original_reference_id: PMID:21146520
  qualifier: involved_in
  review:
    summary: Premeiotic (germline) DNA replication requires the MCM2-7 helicase. In
      mcm-4 mutants the germline retains substantial replication/division capacity
      from maternal/zygotic contribution, but MCM-4 is nonetheless a required
      replication component, including in germline lineages. This NAS annotation
      reflects a curator narrative statement.
    action: KEEP_AS_NON_CORE
    reason: The core role of MCM-4 is general (mitotic) DNA replication; premeiotic
      replication is one specific replication context. The paper notes the germline
      continues replication relatively well in zygotic mcm-4 mutants, so this is a
      legitimate but specialized, non-core facet rather than the defining function.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: In contrast to somatic cells in mcm-4 mutants, the gonad
          continues DNA replication and cell division until late larval development
- term:
    id: GO:0042555
    label: MCM complex
  evidence_type: NAS
  original_reference_id: PMID:21146520
  qualifier: part_of
  review:
    summary: Curator (NAS) statement that MCM-4 is a component of the MCM complex,
      drawn from the primary paper that identifies it as an MCM2-7 subunit.
      Duplicates the strongly supported IBA/IEA/ISS MCM complex annotations.
    action: ACCEPT
    reason: Correct core localization, directly stated in the cited paper.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: encodes an evolutionarily conserved component of the MCM2-7
          pre-RC and replicative helicase complex
- term:
    id: GO:0003678
    label: DNA helicase activity
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: contributes_to
  review:
    summary: DNA helicase activity inferred from sequence similarity to MCM4
      orthologs, with the contributes_to qualifier correctly indicating that the
      activity belongs to the assembled MCM2-7 ring rather than the isolated
      subunit.
    action: ACCEPT
    reason: Correct core molecular function; the contributes_to qualifier is the
      appropriate framing for a single MCM subunit within the helicase.
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
- term:
    id: GO:0003697
    label: single-stranded DNA binding
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: contributes_to
  review:
    summary: ssDNA binding inferred from similarity to MCM4 orthologs; the MCM2-7
      ring engages single-stranded DNA during unwinding. Duplicates the IBA
      annotation to the same term with a contributes_to qualifier.
    action: ACCEPT
    reason: Conserved MCM function; contributes_to appropriately reflects activity
      at the complex level.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: encodes an evolutionarily conserved component of the MCM2-7
          pre-RC and replicative helicase complex
- term:
    id: GO:0042555
    label: MCM complex
  evidence_type: ISS
  original_reference_id: GO_REF:0000024
  qualifier: part_of
  review:
    summary: MCM complex membership inferred from sequence similarity to MCM4
      orthologs. Duplicates the experimentally and phylogenetically supported MCM
      complex annotations.
    action: ACCEPT
    reason: Correct core localization, redundant with stronger evidence lines.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: encodes an evolutionarily conserved component of the MCM2-7
          pre-RC and replicative helicase complex
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:31283754
  qualifier: enables
  review:
    summary: MCM-4 was identified in NMAD-1 immunoprecipitation/mass-spectrometry as
      a putative NMAD-1-binding protein and shown to bind NMAD-1 directly in vitro
      (recombinant His-tagged NMAD-1 pulldown of MCM-4). Notably, the authors were
      unable to confirm the NMAD-1/MCM-4 interaction in vivo (only the NMAD-1/TOP-2
      interaction was confirmed in vivo). The direct in vitro binding supports the
      IPI annotation, but protein binding is an uninformative molecular function
      term per curation guidelines and does not, on its own, define a specific
      activity.
    action: KEEP_AS_NON_CORE
    reason: The direct NMAD-1/MCM-4 interaction is supported by in vitro recombinant
      binding assays, but the in vivo interaction was not confirmed, and a bare
      protein binding term conveys no functional specificity. Retain as supporting
      evidence of a physical interaction but treat as non-core; the core MF terms are
      the helicase/ATPase activities.
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: NMAD-1 directly bound to MTSS-1, TOP-2, and MCM-4,
          components of the DNA replication machinery
      - reference_id: PMID:31283754
        supporting_text: To test whether these candidate NMAD-1 binding proteins
          bound directly to NMAD-1, we performed in vitro binding assays using
          recombinant His-tagged NMAD-1 and GST-tagged or untagged candidate binders
- term:
    id: GO:0007399
    label: nervous system development
  evidence_type: IMP
  original_reference_id: PMID:7262539
  qualifier: involved_in
  review:
    summary: This annotation derives from the classic cell-lineage mutant screen in
      which lin-6(e1466) (= mcm-4) was isolated. The neuronal/lineage phenotypes are
      a pleiotropic downstream consequence of a general postembryonic DNA-replication
      defect in dividing cells, not evidence of a dedicated molecular role of MCM-4
      in nervous system development.
    action: KEEP_AS_NON_CORE
    reason: lin-6/mcm-4 mutants were recovered as postembryonic cell-lineage mutants;
      defective DNA replication in dividing neuroblasts secondarily disrupts nervous
      system development. This is non-core pleiotropy of the core replication defect.
      The supporting reference (PMID:7262539) is abstract-only in our cache, so the
      experimental IMP is retained (not removed) but reframed as non-core. Defer to
      the curator on the underlying assertion.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: The lin-6(e1466) mutation was identified in the first
          systematic search for mutants with defects in the normally invariant
          postembryonic cell lineages of C. elegans
- term:
    id: GO:0008406
    label: gonad development
  evidence_type: IMP
  original_reference_id: PMID:7262539
  qualifier: involved_in
  review:
    summary: Like the nervous system annotation, this reflects pleiotropic
      cell-lineage defects of lin-6/mcm-4 mutants rather than a dedicated gonadal
      developmental function. The gonad/germline actually copes relatively well with
      loss of zygotic mcm-4, continuing replication and division into late larval
      stages.
    action: KEEP_AS_NON_CORE
    reason: Gonad development defects are a secondary consequence of impaired
      postembryonic DNA replication in dividing somatic/germline precursors, not a
      core function of MCM-4. The IMP source (PMID:7262539) is abstract-only in our
      cache, so the experimental annotation is retained and reframed as non-core
      rather than removed.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: the somatic gonad and germline show substantial ability to
          cope with lack of zygotic mcm-4 function
- term:
    id: GO:0040011
    label: locomotion
  evidence_type: IMP
  original_reference_id: PMID:7262539
  qualifier: involved_in
  review:
    summary: Locomotion defects in lin-6/mcm-4 mutants are again a pleiotropic,
      whole-organism consequence of impaired postembryonic cell divisions (slow
      growth, larval arrest/lethality, defective lineages), not evidence that MCM-4
      has a specific molecular role in locomotion.
    action: KEEP_AS_NON_CORE
    reason: Locomotion is a distal phenotype of the general replication/growth defect
      caused by loss of mcm-4; it does not represent a core molecular or cellular
      function. The IMP source (PMID:7262539) is abstract-only in our cache, so the
      annotation is retained and marked non-core rather than removed.
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: These mutants grow slowly and either die during larval
          development or develop into sterile adults
- term:
    id: GO:0005634
    label: nucleus
  evidence_type: IDA
  original_reference_id: PMID:21146520
  qualifier: located_in
  review:
    summary: Direct experimental evidence localizes MCM-4 to the nucleus / nuclear
      chromatin in dividing C. elegans cells. This is the experimental basis for the
      nuclear localization (consistent with the electronic GO:0005634 annotation).
    action: ACCEPT
    reason: Strong direct evidence; nuclear/chromatin localization is expected and
      observed for a pre-RC subunit. MCM-4 is nuclear during interphase with a
      large soluble pool, consistent with regulated licensing.
    additional_reference_ids:
      - file:worm/mcm-4/mcm-4-deep-research-falcon.md
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: The MCM-4 protein is expressed in all dividing cells during
          embryonic and postembryonic development and associates with chromatin in
          late anaphase
      - reference_id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
        supporting_text: MCM-4 is nuclear during interphase, becomes diffuse upon
          nuclear envelope breakdown and is not associated with metaphase chromatin,
          and then reassociates with chromatin in late anaphase
core_functions:
  - description: MCM-4 is a subunit of the heterohexameric MCM2-7 complex, the core
      of the eukaryotic replicative DNA helicase, providing ssDNA-translocating
      helicase activity that unwinds template DNA at replication origins and forks.
    molecular_function:
      id: GO:0003678
      label: DNA helicase activity
    in_complex:
      id: GO:0042555
      label: MCM complex
    directly_involved_in:
      - id: GO:0006260
        label: DNA replication
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: MCM-4 is a component of the minichromosome maintenance
          complex which is responsible for licensing origins for DNA replication and
          is the DNA helicase complex responsible for unwinding the DNA at the
          origins of replication
  - description: Through its conserved MCM AAA+ ATPase module, MCM-4 contributes ATP
      binding and hydrolysis that powers DNA unwinding by the MCM2-7 ring.
    molecular_function:
      id: GO:0016887
      label: ATP hydrolysis activity
    in_complex:
      id: GO:0042555
      label: MCM complex
    supported_by:
      - reference_id: PMID:31283754
        supporting_text: is the DNA helicase complex responsible for unwinding the
          DNA at the origins of replication
  - description: MCM-4 is required for licensing of replication origins and
      initiation of S-phase DNA replication as part of the pre-replication complex,
      and for bulk DNA synthesis in postembryonic somatic lineages.
    molecular_function:
      id: GO:0003678
      label: DNA helicase activity
    directly_involved_in:
      - id: GO:0006270
        label: DNA replication initiation
      - id: GO:1902975
        label: mitotic DNA replication initiation
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: Our results support a conserved function of mcm-4 in
          replication licensing, DNA synthesis and the replication checkpoint
  - description: MCM-4 is required for the DNA replication checkpoint that couples
      mitotic entry to completion of S phase; in its absence cells enter mitosis
      despite incomplete or absent DNA replication.
    directly_involved_in:
      - id: GO:0006260
        label: DNA replication
    supported_by:
      - reference_id: PMID:21146520
        supporting_text: lin-6 is required for the checkpoint that couples M phase
          entry to S phase completion
proposed_new_terms: []
suggested_questions:
  - question: Does the apparent tolerance of the C. elegans germline and somatic
      gonad to loss of zygotic mcm-4 reflect maternal MCM-4 contribution, or a
      genuinely lower requirement for MCM-4 in those lineages?
  - question: What is the functional significance of the physical interaction between
      MCM-4 and the DNA demethylase NMAD-1 (and TOP-2) for replication or repair in
      the germline?
  - question: Why is epidermal (hypodermal) expression of MCM-4 specifically
      sufficient to rescue organismal growth and viability, given that MCM-4 is
      expressed in all dividing cells?
  - question: Does MCM-4, as an obligate subunit of the CMG helicase, contribute to
      the proposed replication-independent / chromatin-handling role of CMG in
      asymmetric cell-fate divergence (reported for the GINS subunit PSF-2), or is
      that function genetically separable from MCM-4?
suggested_experiments:
  - description: Reconstitute or affinity-purify the C. elegans MCM2-7 / CMG complex
      and measure ATP-dependent single-stranded DNA helicase and ATPase activity to
      directly confirm MCM-4 incorporation and biochemical function.
    hypothesis: C. elegans MCM-4 assembles into a functional MCM2-7/CMG complex with
      ATP-dependent DNA helicase activity, as predicted from orthology.
  - description: Use tissue-specific degron/auxin-inducible depletion of MCM-4
      (germline vs. hypodermis vs. neurons) to dissect lineage-specific replication
      requirements and separate the primary replication defect from downstream
      developmental phenotypes.
    hypothesis: The developmental (nervous system, gonad, locomotion) phenotypes are
      secondary to loss of DNA replication in dividing precursors rather than a
      tissue-specific molecular function of MCM-4.
  - description: Map the MCM-4/NMAD-1 interaction interface and test whether NMAD-1
      demethylase activity modulates MCM-4 chromatin loading or replication/repair in
      the germline.
    hypothesis: NMAD-1 regulates MCM-4-dependent replication/repair in the germline
      through a direct physical interaction.
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  findings: []
- id: GO_REF:0000024
  title: Manual transfer of experimentally-verified manual GO annotation data to orthologs
    by curator judgment of sequence similarity
  findings: []
- id: GO_REF:0000033
  title: Annotation inferences using phylogenetic trees
  findings: []
- id: GO_REF:0000044
  title: Gene Ontology annotation based on UniProtKB/Swiss-Prot Subcellular Location
    vocabulary mapping, accompanied by conservative changes to GO terms applied by
    UniProt
  findings: []
- id: GO_REF:0000116
  title: Automatic Gene Ontology annotation based on Rhea mapping
  findings: []
- id: GO_REF:0000120
  title: Combined Automated Annotation using Multiple IEA Methods
  findings: []
- id: file:worm/mcm-4/mcm-4-deep-research-falcon.md
  title: Deep research report on mcm-4 (falcon/Edison)
  findings:
    - statement: MCM-4 contributes as one subunit to the ATPase and helicase
        activities of the MCM2-7/CMG complex, with ATP hydrolysis in the MCM ring
        driving DNA translocation and unwinding.
      supporting_text: MCM proteins carry ATP-binding motifs and are attributed
        ATPase and helicase activities, with ATP hydrolysis within the MCM ring
        driving DNA translocation and unwinding in CMG.
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: LLM-generated deep-research synthesis (falcon/Edison, 51
      citations). Corroborates the lin-6/let-358 = mcm-4 = MCM4 identity, the
      complex-level ATPase/helicase activities, the replication checkpoint role, the
      epidermis-specific requirement, and the chromatin-association dynamics drawn
      from the primary literature. Also flags a 2024 emerging-frontier report
      (Memar et al.) of replication-independent CMG roles in cell-fate divergence,
      studied via the GINS subunit PSF-2 rather than mcm-4 directly.
- id: doi:10.5772/19397
  title: Regulation of DNA synthesis and replication checkpoint activation during
    C. elegans development.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: UNVERIFIED
    review_notes: Ruijtenberg, van den Heuvel & The (2011) book chapter surfaced by
      the falcon deep-research report as additional worm-specific support for MCM-4
      localization dynamics and MCM-4::mCherry reporters. Not independently retrieved
      or read in this review (no PMID; not in the GOA), so marked UNVERIFIED; cited
      indirectly via the deep-research file rather than as a primary supporting_text
      source.
- id: PMID:21146520
  title: C. elegans MCM-4 is a general DNA replication and checkpoint component with
    an epidermis-specific requirement for growth and viability.
  findings:
    - statement: lin-6 corresponds to mcm-4, encoding the C. elegans MCM4 ortholog,
        a conserved subunit of the MCM2-7 pre-RC and replicative helicase complex.
      supporting_text: lin-6 corresponds to mcm-4 and encodes an evolutionarily
        conserved component of the MCM2-7 pre-RC and replicative helicase complex.
    - statement: mcm-4 is required for postembryonic somatic DNA synthesis and for
        the replication checkpoint coupling M-phase entry to S-phase completion.
      supporting_text: lin-6 is required for the checkpoint that couples M phase entry
        to S phase completion
    - statement: MCM-4 is expressed in all dividing cells and associates with
        chromatin in late anaphase.
      supporting_text: The MCM-4 protein is expressed in all dividing cells during
        embryonic and postembryonic development and associates with chromatin in late
        anaphase
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Full-text-verified primary paper that cloned lin-6 = mcm-4 and
      established its role as a conserved MCM2-7 subunit functioning in DNA
      replication and the replication checkpoint, with an epidermis-specific
      requirement. Source of the EXP/IDA/NAS annotations.
- id: PMID:31283754
  title: The demethylase NMAD-1 regulates DNA replication and repair in the Caenorhabditis
    elegans germline.
  findings:
    - statement: NMAD-1 binds MCM-4 directly in vitro (recombinant pulldown); MCM-4
        was identified in NMAD-1 IP/MS as a candidate binder, but the NMAD-1/MCM-4
        interaction was not confirmed in vivo (only NMAD-1/TOP-2 was confirmed in
        vivo).
      supporting_text: NMAD-1 directly bound to MTSS-1, TOP-2, and MCM-4, components
        of the DNA replication machinery
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Full-text-verified. Primarily an NMAD-1 demethylase study; MCM-4
      binds NMAD-1 directly in vitro but the interaction was not confirmed in vivo
      (only TOP-2 was). MCM-4 is described as an MCM2-7 / replicative helicase
      subunit. Source of the IPI protein binding annotation.
- id: PMID:7262539
  title: Isolation and genetic characterization of cell-lineage mutants of the nematode
    Caenorhabditis elegans.
  findings:
    - statement: Classic screen for postembryonic cell-lineage (lin) mutants in which
        lin-6(e1466), later shown to be mcm-4, was isolated.
      supporting_text: The lin-6(e1466) mutation was identified in the first
        systematic search for mutants with defects in the normally invariant
        postembryonic cell lineages of C. elegans
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Abstract-only in cache; identity as the source screen for lin-6 (=
      mcm-4) corroborated by full text of PMID:21146520. Source of the IMP
      developmental annotations (nervous system development, gonad development,
      locomotion), which reflect pleiotropic downstream consequences of the
      replication defect rather than dedicated developmental functions.

mcm-4

Gene Description

Existing Annotations Review

Core Functions

MCM-4 is a subunit of the heterohexameric MCM2-7 complex, the core of the eukaryotic replicative DNA helicase, providing ssDNA-translocating helicase activity that unwinds template DNA at replication origins and forks.

Through its conserved MCM AAA+ ATPase module, MCM-4 contributes ATP binding and hydrolysis that powers DNA unwinding by the MCM2-7 ring.

MCM-4 is required for licensing of replication origins and initiation of S-phase DNA replication as part of the pre-replication complex, and for bulk DNA synthesis in postembryonic somatic lineages.

MCM-4 is required for the DNA replication checkpoint that couples mitotic entry to completion of S phase; in its absence cells enter mitosis despite incomplete or absent DNA replication.

References

Suggested Questions for Experts

Suggested Experiments

Deep Research

Falcon

Research Report: Caenorhabditis elegans mcm-4 (UniProt: Q95XQ8)

Executive summary

1. Identity verification and definitions (critical disambiguation)

1.1 Verified gene/protein identity (worm-specific)

1.2 Key concepts and definitions (current understanding)

2. Molecular function and enzymatic activity of MCM-4 (MCM4)

2.1 What reaction/activity is catalyzed?

2.2 Substrate specificity and directionality

2.3 Complex membership and mechanistic role of MCM-4

3. Biological roles and pathways in C. elegans

3.1 Canonical role: DNA replication licensing and S-phase progression

3.2 Replication checkpoint contributions

3.3 Tissue-specific requirements (key functional insight)

4. Subcellular localization: where MCM-4 acts in the cell

5. Recent developments (prioritizing 2023–2024)

5.1 Mechanistic/structural advances: how origins are unwound and CMG is activated

5.2 New worm biology: replication-independent roles of the CMG complex in fate decisions

5.3 Translational development: CMG/MCM inhibition

6. Current applications and real-world implementations in worm research

6.1 Live reporters and imaging tools

6.2 Assays for DNA replication and cell-cycle analysis

7. Expert synthesis and interpretation

7.1 Why does a “general replication factor” show tissue-specific essentiality?

7.2 Noncanonical CMG/MCM functions: an emerging frontier

Evidence summary table

References (URLs and publication dates)

Artifacts

Citations

📚 Additional Documentation

Notes

mcm-4 (C. elegans) review notes

Identity

Core function (well established)

Key evidence from cached publications

PMID:21146520 (Korzelius et al., 2011, Dev Biol) — full text available, PRIMARY

PMID:31283754 (Wang et al., 2019, PLoS Genet) — full text available, PRIMARY

PMID:7262539 (Sulston & Horvitz, 1981, Genetics) — ABSTRACT ONLY (no full text)

Annotation triage summary (pre-agent)

Deep research status

Thorough integration pass (follow-up)

PR #1514 review fix: protein binding (GO:0005515, IPI)

📄 View Raw YAML