Rfc3 (SPAC27E2.10c) is one of the four small AAA+ ATPase subunits of replication factor C (RFC), the heteropentameric clamp loader that, with ATP, opens the PCNA sliding clamp and loads it onto primer-template junctions so that DNA polymerases delta and epsilon can synthesise processively. It is the fission-yeast member of the RFC subunit 5 subfamily (orthologous to S. cerevisiae Rfc3 and human RFC5) and carries a Walker A ATP-binding motif. The same small subunits partner alternative large subunits to form the RFC-like complexes Rad17-RFC, which loads the Rad9-Rad1-Hus1 (9-1-1) checkpoint clamp, Ctf18-RFC, and Elg1-RFC, the last of which was purified from fission yeast with Rfc3 as a component. rfc3 is essential; the temperature-sensitive rfc3-1 (R216W) allele causes replication defects, chromosome missegregation, sensitivity to hydroxyurea, MMS and radiation, and failure of both the replication and DNA-damage checkpoints. Rfc3 acts in the nucleus on chromatin in chromosomal replication, repair DNA synthesis (including the Uve1-dependent alternative excision repair pathway) and checkpoint signaling.
NAS PMID:16040599 Contrasting effects of Elg1-RFC and Ctf18-RFC inactivation i...
ACCEPT
Summary: Rfc3 participates in DNA replication checkpoint signaling as a subunit of the Rad17-RFC checkpoint clamp loader.
Reason: rfc3-1 cells are defective in both the hydroxyurea-triggered replication checkpoint and the MMS/gamma-ray damage checkpoint, and Rfc3 associates with Rad17 in vivo (PMID:10588638). As a core small subunit of Rad17-RFC, Rfc3 contributes to loading the 9-1-1 checkpoint clamp onto DNA, which is a step of checkpoint signaling itself (sensor loading), not merely a requirement for it. The NAS rows agree with this experimental picture.
From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.
NAS PMID:20505337 Roles of the checkpoint sensor clamp Rad9-Rad1-Hus1 (911)-co...
ACCEPT
Summary: Rfc3 participates in DNA replication checkpoint signaling as a subunit of the Rad17-RFC checkpoint clamp loader.
Reason: rfc3-1 cells are defective in both the hydroxyurea-triggered replication checkpoint and the MMS/gamma-ray damage checkpoint, and Rfc3 associates with Rad17 in vivo (PMID:10588638). As a core small subunit of Rad17-RFC, Rfc3 contributes to loading the 9-1-1 checkpoint clamp onto DNA, which is a step of checkpoint signaling itself (sensor loading), not merely a requirement for it. The NAS rows agree with this experimental picture.
From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.
Summary: Chromatin is where RFC-family clamp loaders act.
Reason: RFC and the RFC-like complexes load or unload sliding clamps on primer-template junctions in chromosomal DNA; chromatin is the compartment in which Rfc3 acts. PomBase's IC is inferred from nuclear localization and RFC membership; is_active_in is appropriate.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: DNA binding is true of the clamp-loader complex but is uninformative relative to clamp loader activity.
Reason: RFC recognises primer-template junctions as part of clamp loading, and Rfc3 belongs to the AAA+ clamp-loader family whose C-terminal domain (IPR008921) is the mapping source. DNA binding is not a parent of DNA clamp loader activity, so it is not redundant in the ontology, but it adds nothing to the core activity and no Rfc3-specific DNA-binding assay exists. Kept as non-core.
Supporting Evidence:
file:SCHPO/rfc3/rfc3-uniprot.txt
DR PANTHER; PTHR11669:SF9; REPLICATION FACTOR C SUBUNIT 5; 1.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: Rfc3 contributes to the clamp loader activity of RFC (PCNA) and Rad17-RFC (9-1-1).
Reason: Rfc3 is in PANTHER subfamily PTHR11669:SF9 (RFC subunit 5) together with S. cerevisiae RFC3 (P38629), human RFC5 (P40937) and Drosophila RfC3; PAINT placed clamp-loader activity at the RFC small-subunit ancestral node (PTN000186209) seeded by yeast and human RFC subunits with direct experimental evidence. The contributes_to qualifier correctly assigns a complex-level activity to one subunit. S. pombe RFC containing Rfc3 supports ATP-dependent processive Pol delta synthesis, and the rfc3-1 (R216W) mutant is defective in replication.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
file:SCHPO/rfc3/rfc3-uniprot.txt
Heteropentamer of subunits rfc1, rfc2, rfc3, rfc4 and rfc5 that forms a complex (RFC) with PCNA in the presence of ATP.
Summary: Rfc3 binds ATP via its P-loop Walker A motif.
Reason: The AAA+ module (IPR003593/IPR003959, Pfam PF00004) and the Walker A ATP-binding site at residues 63-70 support ATP binding by this subunit; ATP binding drives clamp opening and DNA engagement by RFC, and RFC-dependent processive synthesis requires ATP.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
ACCEPT
Summary: Rfc3 is nuclear.
Reason: Rfc3 acts on chromosomal DNA as a subunit of RFC and the RFC-like complexes; the PomBase genome-wide localization screen (HDA), the PAINT inference at a node seeded by yeast, human, fly and trypanosome experimental data, and the UniProt by-similarity location all agree. Nuclear localization is consistent with all known functions.
Reason: Rfc3 acts on chromosomal DNA as a subunit of RFC and the RFC-like complexes; the PomBase genome-wide localization screen (HDA), the PAINT inference at a node seeded by yeast, human, fly and trypanosome experimental data, and the UniProt by-similarity location all agree. Nuclear localization is consistent with all known functions.
Reason: Rfc3 acts on chromosomal DNA as a subunit of RFC and the RFC-like complexes; the PomBase genome-wide localization screen (HDA), the PAINT inference at a node seeded by yeast, human, fly and trypanosome experimental data, and the UniProt by-similarity location all agree. Nuclear localization is consistent with all known functions.
NAS PMID:20505337 Roles of the checkpoint sensor clamp Rad9-Rad1-Hus1 (911)-co...
ACCEPT
Summary: Rfc3 is nuclear.
Reason: Rfc3 acts on chromosomal DNA as a subunit of RFC and the RFC-like complexes; the PomBase genome-wide localization screen (HDA), the PAINT inference at a node seeded by yeast, human, fly and trypanosome experimental data, and the UniProt by-similarity location all agree. Nuclear localization is consistent with all known functions.
Summary: Rfc3 is a core small subunit of replication factor C.
Reason: Rfc3 is one of the four small subunits of RFC (heteropentamer Rfc1-5); it was isolated as the third RFC subunit and its rfc3-1 allele causes replication defects (PMID:10588638). PAINT places RFC complex membership at the RFC small-subunit node, and pombe Rfc3 is in the same PANTHER subfamily (SF9) as S. cerevisiae RFC3 and human RFC5.
Supporting Evidence:
file:SCHPO/rfc3/rfc3-uniprot.txt
Heteropentamer of subunits rfc1, rfc2, rfc3, rfc4 and rfc5 that forms a complex (RFC) with PCNA in the presence of ATP.
From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.
NAS PMID:15952889 Cellular DNA replicases: components and dynamics at the repl...
ACCEPT
Summary: Rfc3 is a core small subunit of replication factor C.
Reason: Rfc3 is one of the four small subunits of RFC (heteropentamer Rfc1-5); it was isolated as the third RFC subunit and its rfc3-1 allele causes replication defects (PMID:10588638). PAINT places RFC complex membership at the RFC small-subunit node, and pombe Rfc3 is in the same PANTHER subfamily (SF9) as S. cerevisiae RFC3 and human RFC5.
Supporting Evidence:
file:SCHPO/rfc3/rfc3-uniprot.txt
Heteropentamer of subunits rfc1, rfc2, rfc3, rfc4 and rfc5 that forms a complex (RFC) with PCNA in the presence of ATP.
From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.
HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ...
KEEP AS NON CORE
Summary: Cytosolic signal from a genome-wide localization screen.
Reason: The ORFeome localization screen recorded cytosolic as well as nuclear signal; the curator saw the image, so the observation is kept. Newly synthesised RFC subunits transit the cytosol, but no function of Rfc3 is known to be performed there, so this is non-core.
Summary: DNA replication is correct but less specific than terms supported for Rfc3.
Reason: Rfc3 participates in DNA replication via PCNA loading for Pol delta/epsilon elongation. The gene already carries the more specific DNA-templated DNA replication (IBA) and DNA strand elongation involved in mitotic DNA replication (IDA); refine to DNA-templated DNA replication, the PAINT-level term.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
NAS PMID:20505337 Roles of the checkpoint sensor clamp Rad9-Rad1-Hus1 (911)-co...
MODIFY
Summary: DNA replication is correct but less specific than terms supported for Rfc3.
Reason: Rfc3 participates in DNA replication via PCNA loading for Pol delta/epsilon elongation. The gene already carries the more specific DNA-templated DNA replication (IBA) and DNA strand elongation involved in mitotic DNA replication (IDA); refine to DNA-templated DNA replication, the PAINT-level term.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: Rfc3 participates in DNA-templated DNA replication as an RFC clamp-loader subunit.
Reason: Rfc3, as an RFC subunit, performs the PCNA-loading step required for processive DNA-templated synthesis by Pol delta (PMID:10748208); rfc3-1 cells are replication-defective (PMID:10588638). The IBA comes from the RFC/clamp-loader node (PTN000186208) seeded by all four pombe small subunits and their yeast/human orthologs. This is the appropriate phylogenetic grain; the more specific strand-elongation terms are also annotated.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
NAS PMID:15952889 Cellular DNA replicases: components and dynamics at the repl...
ACCEPT
Summary: Rfc3 participates in DNA-templated DNA replication as an RFC clamp-loader subunit.
Reason: Rfc3, as an RFC subunit, performs the PCNA-loading step required for processive DNA-templated synthesis by Pol delta (PMID:10748208); rfc3-1 cells are replication-defective (PMID:10588638). The IBA comes from the RFC/clamp-loader node (PTN000186208) seeded by all four pombe small subunits and their yeast/human orthologs. This is the appropriate phylogenetic grain; the more specific strand-elongation terms are also annotated.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: Rfc3 participates in DNA repair by loading PCNA for repair synthesis.
Reason: RFC-dependent PCNA loading is needed for repair DNA synthesis in several pathways; S. pombe RFC is required in the reconstituted alternative excision repair reaction (PMID:10704216), and rfc3-1 cells are sensitive to MMS, gamma and UV irradiation. Because RFC acts in several repair pathways, the broad term is as precise as warranted at the family level; UV-damage excision repair is annotated separately.
A base mispair-containing substrate is repaired in a reaction requiring S. pombe Uve1p, Rad2p, DNA polymerase delta, replication factor C, proliferating cell nuclear antigen, and T4 DNA ligase.
Summary: Rfc3 contributes an ATPase site to the RFC clamp loader.
Reason: Rfc3 is an AAA+ ATPase with an intact Walker A motif; in clamp loaders ATP is hydrolysed at subunit interfaces after clamp closure on DNA, and processive RFC-dependent synthesis requires ATP. No isolated-subunit assay exists for pombe Rfc3, and the activity is coordinated across the pentamer, but ATP hydrolysis by the small subunits' sites is the conserved clamp-loader mechanism.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: Rfc3 contributes an ATPase site to the RFC clamp loader.
Reason: Rfc3 is an AAA+ ATPase with an intact Walker A motif; in clamp loaders ATP is hydrolysed at subunit interfaces after clamp closure on DNA, and processive RFC-dependent synthesis requires ATP. No isolated-subunit assay exists for pombe Rfc3, and the activity is coordinated across the pentamer, but ATP hydrolysis by the small subunits' sites is the conserved clamp-loader mechanism.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Summary: Rfc3 is a subunit of the Rad17-RFC checkpoint clamp loader.
Reason: Rfc3 associates with Rad17 in vivo (PMID:10588638), and the small RFC subunits form Rad17-RFC, which loads the 9-1-1 checkpoint clamp. PAINT propagated this membership from the node PTN000912313 (S. cerevisiae RFC3, the SF9 subfamily ortholog). Core to the checkpoint role.
Association of Rfc3 and Rad17 in vivo and a significant reduction of the phosphorylated form of Chk1 in rfc3-1 cells after treatments with MMS and gamma or UV irradiation suggested that the checkpoint signal emitted by Rfc3 is linked to the downstream checkpoint machinery via Rad17 and Chk1.
NAS PMID:20505337 Roles of the checkpoint sensor clamp Rad9-Rad1-Hus1 (911)-co...
ACCEPT
Summary: Rfc3 is a subunit of the Rad17-RFC checkpoint clamp loader.
Reason: Rfc3 associates with Rad17 in vivo (PMID:10588638), and the small RFC subunits form Rad17-RFC, which loads the 9-1-1 checkpoint clamp. PAINT propagated this membership from the node PTN000912313 (S. cerevisiae RFC3, the SF9 subfamily ortholog). Core to the checkpoint role.
Association of Rfc3 and Rad17 in vivo and a significant reduction of the phosphorylated form of Chk1 in rfc3-1 cells after treatments with MMS and gamma or UV irradiation suggested that the checkpoint signal emitted by Rfc3 is linked to the downstream checkpoint machinery via Rad17 and Chk1.
Reason: Ctf18-RFC shares the four small RFC subunits (shown for S. cerevisiae and human, and propagated by PAINT from the SF9 ortholog S. cerevisiae RFC3 at node PTN000912313). In fission yeast, Ctf18-RFC is genetically required when RFC is compromised and acts redundantly with Rad17-RFC at telomeres, but direct purification of pombe Ctf18-RFC is not reported in the cited papers. Membership is well supported by phylogeny; its role (cohesion establishment, PCNA loading) is peripheral to Rfc3's core RFC function, so non-core.
Inactivation of Ctf18-RFC by the deletion of ctf18+, dcc1+ or ctf8+ is lethal in an rfc1-44 background showing that full Ctf18-RFC function is required in the absence of fully functional RFC.
NAS PMID:20505337 Roles of the checkpoint sensor clamp Rad9-Rad1-Hus1 (911)-co...
KEEP AS NON CORE
Summary: Rfc3 is a shared subunit of Ctf18-RFC.
Reason: Ctf18-RFC shares the four small RFC subunits (shown for S. cerevisiae and human, and propagated by PAINT from the SF9 ortholog S. cerevisiae RFC3 at node PTN000912313). In fission yeast, Ctf18-RFC is genetically required when RFC is compromised and acts redundantly with Rad17-RFC at telomeres, but direct purification of pombe Ctf18-RFC is not reported in the cited papers. Membership is well supported by phylogeny; its role (cohesion establishment, PCNA loading) is peripheral to Rfc3's core RFC function, so non-core.
Inactivation of Ctf18-RFC by the deletion of ctf18+, dcc1+ or ctf8+ is lethal in an rfc1-44 background showing that full Ctf18-RFC function is required in the absence of fully functional RFC.
Summary: Rfc3 is a subunit of Elg1-RFC (directly shown in S. pombe).
Reason: TAP purification of fission-yeast Elg1-RFC followed by mass spectrometry identified Rfc3 among its five subunits (PMID:16040599), directly establishing membership; PAINT and ARBA concur.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
IDA PMID:16040599 Contrasting effects of Elg1-RFC and Ctf18-RFC inactivation i...
ACCEPT
Summary: Rfc3 is a subunit of Elg1-RFC (directly shown in S. pombe).
Reason: TAP purification of fission-yeast Elg1-RFC followed by mass spectrometry identified Rfc3 among its five subunits (PMID:16040599), directly establishing membership; PAINT and ARBA concur.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
Summary: Rfc3 is a subunit of Elg1-RFC (directly shown in S. pombe).
Reason: TAP purification of fission-yeast Elg1-RFC followed by mass spectrometry identified Rfc3 among its five subunits (PMID:16040599), directly establishing membership; PAINT and ARBA concur.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
NAS PMID:16040599 Contrasting effects of Elg1-RFC and Ctf18-RFC inactivation i...
ACCEPT
Summary: Rfc3 is a subunit of Elg1-RFC (directly shown in S. pombe).
Reason: TAP purification of fission-yeast Elg1-RFC followed by mass spectrometry identified Rfc3 among its five subunits (PMID:16040599), directly establishing membership; PAINT and ARBA concur.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
IC PMID:16040599 Contrasting effects of Elg1-RFC and Ctf18-RFC inactivation i...
KEEP AS NON CORE
Summary: Clamp unloading is an Elg1-RFC complex activity to which Rfc3 can at most contribute.
Reason: The IC is inferred from Rfc3 membership of Elg1-RFC (GO:0031391). The cited 2005 paper only raises unloading as a hypothesis; Elg1-RFC PCNA unloading was later established in budding yeast and human (ATAD5-RLC), and is driven by the Elg1 large subunit. PAINT curators propagated Elg1-RFC membership to the RFC small subunits but did not propagate clamp unloader activity to them, which is consistent with treating unloading as an Elg1-dependent, complex-level activity. The annotation is plausible as a contribution of a shared subunit but would be better expressed with contributes_to; kept as non-core rather than removed because complex membership is direct.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
IDA PMID:10704216 In vitro reconstitution of the Schizosaccharomyces pombe alt...
ACCEPT
Summary: RFC-containing Rfc3 participates in UV-damage (alternative) excision repair synthesis.
Reason: S. pombe RFC is required, with PCNA and Pol delta, for the repair-synthesis step of the reconstituted Uve1-initiated alternative excision repair pathway (PMID:10704216); RFC performs the PCNA-loading step of that pathway, so this is participation, not mere requirement. The ARBA row agrees.
A base mispair-containing substrate is repaired in a reaction requiring S. pombe Uve1p, Rad2p, DNA polymerase delta, replication factor C, proliferating cell nuclear antigen, and T4 DNA ligase.
Summary: RFC-containing Rfc3 participates in UV-damage (alternative) excision repair synthesis.
Reason: S. pombe RFC is required, with PCNA and Pol delta, for the repair-synthesis step of the reconstituted Uve1-initiated alternative excision repair pathway (PMID:10704216); RFC performs the PCNA-loading step of that pathway, so this is participation, not mere requirement. The ARBA row agrees.
A base mispair-containing substrate is repaired in a reaction requiring S. pombe Uve1p, Rad2p, DNA polymerase delta, replication factor C, proliferating cell nuclear antigen, and T4 DNA ligase.
GO:1902983 DNA strand elongation involved in mitotic DNA replication
IDA PMID:10748208 Fidelity of eucaryotic DNA polymerase delta holoenzyme from ...
ACCEPT
Summary: Rfc3 (as RFC) participates in DNA strand elongation during mitotic replication.
Reason: Purified S. pombe RFC loads PCNA for processive, ATP-dependent Pol delta synthesis (PMID:10748208): this is the strand-elongation step to which Rfc3 contributes, and rfc3-1 cells are replication-defective. The ARBA row agrees.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Pulsed-field gel electrophoresis suggested that rfc3-1 cells had defects in DNA replication.
GO:1902983 DNA strand elongation involved in mitotic DNA replication
IEA GO_REF:0000117
ACCEPT
Summary: Rfc3 (as RFC) participates in DNA strand elongation during mitotic replication.
Reason: Purified S. pombe RFC loads PCNA for processive, ATP-dependent Pol delta synthesis (PMID:10748208): this is the strand-elongation step to which Rfc3 contributes, and rfc3-1 cells are replication-defective. The ARBA row agrees.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
Pulsed-field gel electrophoresis suggested that rfc3-1 cells had defects in DNA replication.
GO:1903460 mitotic DNA replication leading strand elongation
ISO GO_REF:0000024
ACCEPT
Summary: Rfc3 participates in leading-strand elongation via PCNA loading for Pol epsilon/delta.
Reason: Curator transfer from S. cerevisiae RFC3 (SGD:S000005234), which is in the same PANTHER subfamily (SF9) and is the direct ortholog. RFC loads PCNA for both leading- and lagging-strand synthesis; the leading-strand term is supported in budding yeast and is consistent with pombe RFC supporting processive Pol delta synthesis.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
file:SCHPO/rfc3/rfc3-uniprot.txt
DR PANTHER; PTHR11669:SF9; REPLICATION FACTOR C SUBUNIT 5; 1.
Core Functions
ATPase subunit of replication factor C that contributes to ATP-dependent loading of PCNA onto primer-template DNA, enabling processive DNA synthesis in chromosomal replication and repair.
Processive synthesis occurred in the presence of PCNA, RFC, and Escherichia coli single strand DNA-binding protein (SSB) and required the presence of ATP.
file:SCHPO/rfc3/rfc3-uniprot.txt
Heteropentamer of subunits rfc1, rfc2, rfc3, rfc4 and rfc5 that forms a complex (RFC) with PCNA in the presence of ATP.
A base mispair-containing substrate is repaired in a reaction requiring S. pombe Uve1p, Rad2p, DNA polymerase delta, replication factor C, proliferating cell nuclear antigen, and T4 DNA ligase.
Pulsed-field gel electrophoresis suggested that rfc3-1 cells had defects in DNA replication.
Small subunit of the Rad17-RFC checkpoint clamp loader, contributing to loading of the 9-1-1 clamp and to replication and DNA-damage checkpoint signaling.
From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor.
Association of Rfc3 and Rad17 in vivo and a significant reduction of the phosphorylated form of Chk1 in rfc3-1 cells after treatments with MMS and gamma or UV irradiation suggested that the checkpoint signal emitted by Rfc3 is linked to the downstream checkpoint machinery via Rad17 and Chk1.
Instead of PCNA, Rad17–RFC loads the 9-1-1 complex onto DNA.
Structural small subunit of the alternative RFC-like complex Elg1-RFC, whose membership (Elg1 with Rfc2-5) is directly established in fission yeast by TAP purification and mass spectrometry. The PCNA-unloading activity of Elg1-RFC is driven by the Elg1 large subunit and has not been dissected for Rfc3 itself; membership of Ctf18-RFC is supported by phylogeny and genetics but not shown biochemically in S. pombe, and is kept as non-core.
No additional proteins were identified in these purified preparations, strongly suggesting that Elg1–RFC comprises the Elg1, Rfc2, Rfc3, Rfc4 and Rfc5 proteins only.
Q: Should the PomBase IC annotation of Rfc3 to DNA clamp unloader activity (GO:0061860) carry contributes_to, given that unloading is driven by the Elg1 large subunit and PAINT did not propagate this activity to the shared small subunits?
Suggested Experiments
Experiment: Test whether the Walker A lysine of pombe Rfc3 is required in vivo (rfc3 K->E allele complementation) and for ATP-dependent PCNA loading by reconstituted RFC, and whether rfc3-1 (R216W) selectively impairs Rad17-RFC 9-1-1 loading versus RFC PCNA loading.
External Prediction Reviews
These computational predictions are reviewed separately from the GOA annotation set used for this review. The assessments below are from this project and do not constitute official GO annotations or endorsement by GO/UniProt. They are not included in the existing annotation review above.
The single GO prediction, DNA replication, describes established Rfc3 biology and is already annotated to the gene (CNN); the gene review prefers the more specific DNA-templated DNA replication.
Review rationale: The rfc3-1 temperature-sensitive mutant is defective in DNA replication (PMID:10588638), and purified fission-yeast RFC is required with PCNA for processive DNA synthesis by Pol delta (PMID:10748208). Replication is an established function of this clamp-loader subunit. The gene already carries DNA replication itself in GOA (IEA and NAS), so the prediction is correct and not novel (CNN). The gene review refines that row to the more specific DNA-templated DNA replication.
Supporting Evidence:
PMID:10588638: "From these results, we conclude that rfc3(+) is required not only for DNA replication but also for replication and damage checkpoint controls, probably functioning as a checkpoint sensor."