Anillin-related scaffold protein (also called Dmf1) that positions the cytokinetic division plane in fission yeast. During interphase Mid1 is predominantly nuclear; at the onset of mitosis it is exported from the nucleus and forms a broad cortical band of punctate "nodes" at the cell middle, overlying the nucleus, thereby coupling the future division site to nuclear position. Mid1 serves as a recruitment platform that brings contractile actomyosin ring (CAR) components - myosin-II (Myo2), the IQGAP Rng2, the F-BAR protein Cdc15, formin Cdc12, the SAD-family kinase Cdr2, and the Clp1/Cdc14 phosphatase - to the medial cortex, where these nodes condense into the contractile ring. Mid1 binds the plasma membrane through a C-terminal C2-pleckstrin-homology (PH) module that prefers PI(4,5)P2 and through an amphipathic helix adjacent to its nuclear localization signal; its intrinsically disordered N-terminal half oligomerizes and can undergo liquid- liquid phase separation, properties suited to scaffolding other node proteins. Mid1 localization and activity are cell-cycle regulated by phosphorylation: Plo1 (polo-like kinase) phosphorylation promotes its nuclear export and ring competence, and the septation initiation network kinase Sid2 phosphorylates Mid1 to remove it from the cortex at the onset of ring constriction.
| GO Term | Evidence | Action | Reason |
|---|---|---|---|
| GO:0000281 mitotic cytokinesis | IBA GO_REF:0000033 | ACCEPT | Summary: Mid1 is a well-established participant in mitotic cytokinesis, positioning the division plane and scaffolding contractile-ring assembly. The phylogenetic (IBA) involvement in mitotic cytokinesis is fully consistent with extensive experimental data in S. pombe and with the anillin family. Reason: Phylogenetic inference matches the abundant experimental evidence that mid1 acts in mitotic cytokinesis; this is a non-core but accurate parent process term for the gene. Supporting Evidence: PMID:22918943 orderly assembly of the contractile ring in wild-type cells depends on Mid1p to recruit myosin-II, Rng2p, and Cdc15p to nodes and to place cytokinetic nodes around the cell equator. |
| GO:0005826 actomyosin contractile ring | IBA GO_REF:0000033 | ACCEPT | Summary: Mid1 localizes to and is active in the medial actomyosin contractile ring. Experimental S. pombe data place Mid1 in the mitotic contractile ring; the phylogenetic localization is correct, although the more specific mitotic-ring terms (GO:0110085) are also annotated experimentally. Reason: Consistent with experimental IDA annotations to mitotic actomyosin contractile ring; the IBA general term is accurate. Supporting Evidence: PMID:9852154 Plo1p localizes to the spindle pole bodies and spindles of mitotic cells and also to the medial ring at the time of its formation. |
| GO:0000915 actomyosin contractile ring assembly | IBA GO_REF:0000033 | ACCEPT | Summary: Mid1 is required for orderly assembly of the contractile ring by recruiting ring components to medial nodes. The phylogenetic involvement in contractile ring assembly is accurate; the organism-specific mitotic term (GO:1903475) is also annotated experimentally. Reason: Matches experimental IMP evidence for ring assembly; appropriate general process term. Supporting Evidence: PMID:16864655 the anillin-like protein Mid1p establishes a broad band of small dots or nodes in the cortex near the nucleus. These nodes mature by the addition of conventional myosin II (Myo2p, Cdc4p, and Rlc1p), IQGAP (Rng2p), pombe Cdc15 homology protein (Cdc15p), and formin (Cdc12p). |
| GO:0031106 septin ring organization | IBA GO_REF:0000033 | REMOVE | Summary: Septin ring organization is the characterized function of the paralog mid2 (anillin-like, SPCC18B5.04), not of mid1. Mid1 organizes the contractile actomyosin ring and division-site nodes, but there is no experimental evidence that it organizes the septin ring. This IBA term most likely reflects mis-propagation across the anillin family and a mid1/mid2 conflation. Reason: No experimental support for mid1 in septin ring organization; this is the established role of the paralog mid2. The phylogenetic propagation conflates the two pombe anillins and over-annotates mid1. |
| GO:0005634 nucleus | IEA GO_REF:0000044 | ACCEPT | Summary: Mid1 is nuclear during interphase, so nuclear localization is correct. This IEA term is redundant with multiple experimental IDA nucleus annotations but is accurate. Reason: Nuclear localization is experimentally documented; the subcellular- location-derived IEA is corroborated. Supporting Evidence: PMID:8946912 In wild-type cells, Dmf1p is nuclear during interphase, and relocates to form a medial ring at the cell cortex coincident with the onset of mitosis. |
| GO:0005856 cytoskeleton | IEA GO_REF:0000044 | MODIFY | Summary: The generic "cytoskeleton" term is an imprecise UniProt subcellular- location mapping. Mid1's relevant cytoskeletal location is the actomyosin contractile ring / cortical nodes, captured by more specific experimental terms (GO:0110085, GO:0071341). The broad term should be replaced by the specific structures. Reason: "cytoskeleton" is uninformatively general; experimentally Mid1 is in the mitotic actomyosin contractile ring and medial cortical nodes. Proposed replacements: mitotic actomyosin contractile ring medial cortical node Supporting Evidence: PMID:16864655 the anillin-like protein Mid1p establishes a broad band of small dots or nodes in the cortex near the nucleus. |
| GO:0005938 cell cortex | IEA GO_REF:0000044 | MODIFY | Summary: Mid1 localizes to the medial cell cortex, so the cortex term is correct but general. The more specific experimentally supported terms are "medial cortex" (GO:0031097) and "medial cortical node" (GO:0071341). Reason: Accurate but imprecise; the medial cortex / medial cortical node terms are experimentally supported and more informative. Proposed replacements: medial cortex medial cortical node Supporting Evidence: PMID:10930468 mid1 protein (mid1p) shuttles between the nucleus and a cortical medial broad band during interphase and early mitosis. |
| GO:0005634 nucleus | EXP PMID:10930468 Analysis of mid1p, a protein required for placement of the c... | ACCEPT | Summary: Direct experimental localization shows Mid1 shuttles between the nucleus and a cortical medial band. Nuclear localization during interphase is well documented in this study, including NLS/NES mutational analysis. Reason: Robust IDA/EXP nuclear localization with functional NLS/NES dissection. Supporting Evidence: PMID:10930468 NES mutations caused mid1p accumulation in the nucleus and loss of function. |
| GO:0005634 nucleus | EXP PMID:12186944 Cytokinetic actomyosin ring formation and septation in fissi... | ACCEPT | Summary: Mid1/Dmf1 localization to the nucleus is consistent with the body of evidence. This study examined microtubule-dependent delays in Mid1/Dmf1 cortical recruitment but also documents its nuclear pool. Reason: Nuclear localization corroborated across many studies; accept. Supporting Evidence: PMID:12186944 Microtubule depolymerisation also delayed the localisation of other CAR components such as actin and Mid1/Dmf1. |
| GO:0005634 nucleus | EXP PMID:19427212 Spatial control of cytokinesis by Cdr2 kinase and Mid1/anill... | ACCEPT | Summary: Nuclear localization is central to this study, which shows that Mid1 nuclear export links division-plane position to nuclear position. Accept. Reason: Mid1 nuclear pool and its regulated export are directly demonstrated. Supporting Evidence: PMID:19427212 the positive signaling from the nucleus is based on Mid1 nuclear export, which links division-plane position to nuclear position during early mitosis. |
| GO:0005634 nucleus | EXP PMID:19474789 A spatial gradient coordinates cell size and mitotic entry i... | ACCEPT | Summary: Consistent with Mid1's interphase nuclear localization and its presence in medial cortical nodes. Accept the nucleus localization. Reason: Nuclear localization corroborated; this study primarily characterizes Mid1 in cortical nodes with Cdr2/Wee1/Cdr1. Supporting Evidence: PMID:19474789 This network is located at cortical nodes in the middle of interphase cells, and these nodes contain the Cdk1 inhibitor Wee1, the Wee1-inhibitory kinases Cdr1 (also known as Nim1) and Cdr2, and the anillin-like protein Mid1. |
| GO:1903475 mitotic actomyosin contractile ring assembly | EXP PMID:19075108 Assembly of normal actomyosin rings in the absence of Mid1p ... | ACCEPT | Summary: Mid1 is required for mitotic actomyosin contractile ring assembly, a core function supported by many studies. The supporting publication (PMID:19075108) is not in the local cache and could not be read directly, but the annotated function is strongly corroborated by other experimental annotations (PMID:9852154 IMP, PMID:15184401 IMP, PMID:22918943). Reason: Core function with overwhelming independent experimental support; the single uncached reference does not undermine an otherwise robust annotation. Supporting Evidence: PMID:22918943 Ring assembly is unreliable and slow without Mid1p because the scattered Cdc12p nodes generate strands spread widely beyond the equator |
| GO:0008289 lipid binding | EXP PMID:15572668 C-terminal anchoring of mid1p to membranes stabilizes cytoki... | ACCEPT | Summary: Mid1 binds the medial cortex membrane via its C-terminus, including an amphipathic helix predicted to insert into the lipid bilayer. Lipid binding is experimentally supported; the more specific PI(4,5)P2 binding (GO:0005546) is also annotated. Reason: Direct membrane/lipid association demonstrated; general lipid binding is accurate. Supporting Evidence: PMID:15572668 mid1p C-terminus association with the cortex requires a putative amphipathic helix adjacent to mid1p nuclear localization sequence (NLS), which is predicted to insert directly into the lipid bilayer. |
| GO:1902408 mitotic cytokinesis, division site positioning | EXP PMID:19427212 Spatial control of cytokinesis by Cdr2 kinase and Mid1/anill... | ACCEPT | Summary: This is a core function of Mid1: defining the position of the division plane at the medial cortex via nuclear export and Cdr2-dependent cortical anchoring. Strongly supported. Reason: Directly demonstrated division-site positioning function. Supporting Evidence: PMID:19427212 These signals control the localization of the anillin-like protein Mid1, which defines the position of the division plane at the medial cortex, where it recruits contractile-ring components at mitosis onset. |
| GO:0005546 phosphatidylinositol-4,5-bisphosphate binding | IDA PMID:25959226 Mechanistic insights into the anchorage of the contractile r... | ACCEPT | Summary: Crystal structures and functional analysis show that Mid1 binds membranes through a cryptic C2 domain, and dimerization confers high affinity and preference for PI(4,5)P2, which anchors Mid1 at the division plane. This specific lipid-binding activity is well supported. Reason: Direct biochemical/structural demonstration of PI(4,5)P2 binding. Supporting Evidence: PMID:25959226 Dimerization of Mid1 leads to high affinity and preference for PI(4,5)P2, which stably anchors Mid1 at the division plane, bypassing the requirement for Rho GTPase. |
| GO:0106006 cytoskeletal protein-membrane anchor activity | EXP PMID:25959226 Mechanistic insights into the anchorage of the contractile r... | ACCEPT | Summary: Mid1 anchors the contractile (cytoskeletal) ring to the plasma membrane via its C2-PH membrane-binding module, a defining molecular function of anillin/Mid1 family scaffolds. Well supported. Reason: Structural and functional data show Mid1 tethers the contractile ring to membrane lipids; appropriate MF term. Supporting Evidence: PMID:25959226 Anillins and Mid1 are scaffold proteins that play key roles in anchorage of the contractile ring at the cell equator during cytokinesis in animals and fungi, respectively. |
| GO:1902408 mitotic cytokinesis, division site positioning | EXP PMID:15928091 Dynamic positioning of the fission yeast cell division plane... | ACCEPT | Summary: Division-site positioning is a core, repeatedly validated Mid1 function. The supporting paper (PMID:15928091, "Dynamic positioning of the fission yeast cell division plane") is not in the local cache, but the annotated function is independently and strongly supported by other experimental annotations (PMID:8946912, PMID:19427212, PMID:9852154). Reason: Core function with extensive corroborating experimental evidence; the uncached reference does not weaken it. Supporting Evidence: PMID:8946912 Dmf1 mutants complete mitosis and initiate septum formation, but the septa that form are positioned at random locations and angles in the cell, rather than in the middle. |
| GO:0005515 protein binding | IPI PMID:31243991 The Functionally Important N-Terminal Half of Fission Yeast ... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" is uninformative. The interactor here (Myo2, UniProtKB:Q9USI6) reflects Mid1's role in recruiting/anchoring myosin-II to nodes, which is better captured by the protein-membrane adaptor / scaffold molecular functions. Keep only as supporting interaction evidence, not as an informative MF. Reason: Generic protein binding term provides no functional insight; the meaningful activity (scaffolding/anchoring Myo2) is captured by more specific terms such as GO:0043495 and GO:0140693. Supporting Evidence: PMID:31243991 Mid1p recruits in succession myosin-II (Myo2p heavy chain, Cdc4p light chain, Rlc1p1 regulatory light chain together called Myo2, UniProtKB Q9USI6), IQGAP Rng2p, F-BAR protein (FER/CDP4 homology domain-Bin-Amphiphysin-Rvs-like protein) Cdc15p and formin Cdc12p |
| GO:0140693 molecular condensate scaffold activity | IDA PMID:31243991 The Functionally Important N-Terminal Half of Fission Yeast ... | ACCEPT | Summary: The intrinsically disordered N-terminal half of Mid1 (Mid1p-N452) demixes into liquid droplets and has properties suited to scaffolding other node proteins. This molecular condensate scaffold activity is directly supported. Reason: Purified Mid1 N-terminus undergoes phase separation with scaffolding properties, consistent with its role in organizing cytokinetic nodes. Supporting Evidence: PMID:31243991 Purified Mid1p-N452 demixes into liquid droplets at concentrations far below its concentration in nodes. These physical properties are appropriate for scaffolding other proteins in nodes. |
| GO:0106006 cytoskeletal protein-membrane anchor activity | EXP PMID:21376595 IQGAP-related Rng2p organizes cortical nodes and ensures pos... | ACCEPT | Summary: Mid1 anchors actomyosin-ring components to the medial cortex by recruiting them to membrane-associated nodes. This study shows Mid1 recruits Rng2 to cortical nodes, consistent with a cytoskeletal protein-membrane anchor function. Accept. Reason: Supports Mid1's role in tethering ring components at the cortex via nodes. Supporting Evidence: PMID:21376595 Mid1p arrives first at the medial cortex and recruits actomyosin ring components to node-like structures |
| GO:0106006 cytoskeletal protein-membrane anchor activity | IPI PMID:15184401 Myosin-II reorganization during mitosis is controlled tempor... | ACCEPT | Summary: Mid1 anchors dephosphorylated Myo2 (the cytoskeletal motor) at the medial cortex (membrane), directly supporting cytoskeletal protein-membrane anchor activity. The IPI interactor is Myo2 (PomBase:SPCC645.05c). Reason: Physical anchoring of Myo2 at the cortex is directly demonstrated. Supporting Evidence: PMID:15184401 dephosphorylated Myo2 is anchored by Mid1 at the medial cortex and promotes the ring assembly in cooperation with F-actin. |
| GO:1903475 mitotic actomyosin contractile ring assembly | IMP PMID:15184401 Myosin-II reorganization during mitosis is controlled tempor... | ACCEPT | Summary: Mid1 is required for proper accumulation of Myo2 and ring placement; loss of Mid1 spatial function impairs contractile ring assembly. Core function, strongly supported by IMP. Reason: Direct mutant phenotype evidence for Mid1's role in ring assembly via Myo2 anchoring. Supporting Evidence: PMID:15184401 The accumulation of Myo2 requires the anillin homologue Mid1 that functions in proper ring placement. |
| GO:0005634 nucleus | IDA PMID:8946912 The dmf1/mid1 gene is essential for correct positioning of t... | ACCEPT | Summary: The founding study showing Dmf1/Mid1 is nuclear during interphase and relocates to a medial cortical ring at mitosis onset. Nuclear localization is directly observed. Reason: Original IDA demonstration of interphase nuclear localization. Supporting Evidence: PMID:8946912 In wild-type cells, Dmf1p is nuclear during interphase, and relocates to form a medial ring at the cell cortex coincident with the onset of mitosis. |
| GO:0031097 medial cortex | IDA PMID:8946912 The dmf1/mid1 gene is essential for correct positioning of t... | ACCEPT | Summary: Mid1/Dmf1 forms a medial cortical ring/band at mitosis onset. Medial cortex localization is directly observed and is a core localization for its division-site positioning function. Reason: Original IDA evidence for medial cortex localization. Supporting Evidence: PMID:8946912 relocates to form a medial ring at the cell cortex coincident with the onset of mitosis. |
| GO:0071341 medial cortical node | IDA PMID:22918943 Anillin-related protein Mid1p coordinates the assembly of th... | ACCEPT | Summary: Mid1 is a defining component of medial cortical (cytokinetic) nodes that mature into the contractile ring. Directly observed in live-cell imaging. Core localization. Reason: Direct imaging shows Mid1 in cortical nodes that condense into the ring. Supporting Evidence: PMID:22918943 cortical nodes containing the protein Blt1p and several kinases appear early in G2, mature into cytokinetic nodes by adding anillin Mid1p, myosin-II, formin Cdc12p, and other proteins, and condense into a contractile ring |
| GO:0005515 protein binding | IPI PMID:30853434 NDR Kinase Sid2 Drives Anillin-like Mid1 from the Membrane t... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" with interactor PomBase:SPAC31A2.16 (Sid2/Mob1 SIN kinase complex). The biologically meaningful relationship is that Sid2 phosphorylates Mid1 to remove it from the cortex; the generic MF term is uninformative. Reason: Uninformative generic term; the meaningful interaction (Sid2-mediated regulation) is better represented as a phosphorylation/regulatory relationship rather than as a molecular function of mid1. Supporting Evidence: PMID:30853434 We report that the terminal SIN kinase, Sid2 [6], phosphorylates Mid1 to drive its removal from the cortex at CR constriction onset. |
| GO:0005634 nucleus | IDA PMID:30853434 NDR Kinase Sid2 Drives Anillin-like Mid1 from the Membrane t... | ACCEPT | Summary: Mid1 nuclear localization is consistent with its documented interphase nuclear pool. Accept. Reason: Nuclear localization corroborated across studies. Supporting Evidence: PMID:30853434 The anillin-like protein Mid1 localizes to nodes and is required for CR assembly at mid-cell |
| GO:0071341 medial cortical node | IDA PMID:30853434 NDR Kinase Sid2 Drives Anillin-like Mid1 from the Membrane t... | ACCEPT | Summary: Mid1 localizes to medial cortical (interphase/cytokinetic) nodes; this study shows Sid2 phosphorylation controls its node/cortex residence. Directly observed. Core localization. Reason: Direct imaging of Mid1 in nodes; central to the study. Supporting Evidence: PMID:30853434 A Mid1 mutant that cannot be phosphorylated by Sid2 remains cortical during cytokinesis, over-accumulates in interphase nodes following cell division |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:30853434 NDR Kinase Sid2 Drives Anillin-like Mid1 from the Membrane t... | ACCEPT | Summary: Mid1 localizes to the mitotic contractile ring before being removed at constriction onset. Directly observed. Core localization. Reason: Direct imaging of Mid1 at the contractile ring. Supporting Evidence: PMID:30853434 When CR constriction begins, Mid1 leaves the division site. |
| GO:0071341 medial cortical node | IDA PMID:16864655 Assembly of the cytokinetic contractile ring from a broad ba... | ACCEPT | Summary: Mid1 establishes a broad band of cortical nodes in the medial cortex, directly observed by live-cell imaging. Core localization. Reason: Direct imaging of Mid1-established medial cortical nodes. Supporting Evidence: PMID:16864655 the anillin-like protein Mid1p establishes a broad band of small dots or nodes in the cortex near the nucleus. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:16864655 Assembly of the cytokinetic contractile ring from a broad ba... | ACCEPT | Summary: Mid1-established nodes coalesce into the mitotic contractile ring; Mid1 is a ring-resident component during assembly. Directly observed. Reason: Direct imaging places Mid1 in nodes that form the contractile ring. Supporting Evidence: PMID:16864655 The nodes coalesce laterally into a compact ring when Cdc12p and profilin Cdc3p stimulate actin polymerization. |
| GO:1903475 mitotic actomyosin contractile ring assembly | IGI PMID:16687577 Cell cycle-dependent roles for the FCH-domain protein Cdc15p... | ACCEPT | Summary: Genetic interaction with cdc15 (PomBase:SPAC20G8.05c) shows ring formation upon metaphase arrest depends on Mid1 when Cdc15 is nonfunctional, supporting Mid1's role in mitotic ring assembly. Accept. Reason: Genetic-interaction evidence consistent with Mid1's core ring-assembly function. Supporting Evidence: PMID:16687577 In the absence of functional Cdc15p, ring formation upon metaphase arrest depends on the anillin-like Mid1p. |
| GO:0120104 mitotic actomyosin contractile ring, proximal layer | IDA PMID:28914606 Nanoscale architecture of the Schizosaccharomyces pombe cont... | ACCEPT | Summary: Super-resolution/FRET mapping places membrane-binding scaffolds (which include Mid1) in the membrane-proximal layer (0-80 nm) of the contractile ring. The specific proximal-layer localization is directly supported. Reason: Nanoscale architecture analysis localizes Mid1 to the membrane-proximal ring layer. Supporting Evidence: PMID:28914606 The most membrane-proximal layer (0-80 nm) is composed of membrane-binding scaffolds, formin, and the tail of the essential myosin-II. |
| GO:0005634 nucleus | IDA PMID:14602073 Spatial and temporal pathway for assembly and constriction o... | ACCEPT | Summary: Mid1 migrates from the nucleus to specify the division-site band; nuclear localization is directly observed in this temporal-pathway study. Accept. Reason: Direct imaging of the nuclear Mid1 pool prior to cortical migration. Supporting Evidence: PMID:14602073 the anillin-like protein (Mid1p) migrates from the nucleus and specifies a broad band of cortex around the equator as the division site. |
| GO:0071341 medial cortical node | IDA PMID:14602073 Spatial and temporal pathway for assembly and constriction o... | ACCEPT | Summary: Mid1 specifies a broad band of cortical nodes at the equator early in the cytokinesis pathway. Directly observed. Core localization. Reason: Direct imaging of Mid1-specified equatorial cortical band/nodes. Supporting Evidence: PMID:14602073 the anillin-like protein (Mid1p) migrates from the nucleus and specifies a broad band of cortex around the equator as the division site. |
| GO:0031106 septin ring organization | IMP PMID:15385632 Requirements of fission yeast septins for complex formation,... | REMOVE | Summary: This IMP annotation cites PMID:15385632. Unlike the abstract-only cases where we defer to curators, this paper's FULL TEXT is cached and was checked directly: it contains zero mentions of mid1 and six of mid2, and characterizes S. pombe septins (Spns1-4) together with the anillin Mid2p. Septin ring organization is the established function of the paralog mid2 (SPCC18B5.04); Mid1 instead positions the actomyosin contractile ring and division-site nodes. On the strength of this full-text check this looks like a mid1/mid2 paralog conflation, flagged for PomBase re-assignment to mid2. Reason: Full text of the cited paper (cached, verified) discusses septins and Mid2p with no mention of mid1; septin ring organization is a mid2 function and Mid1 has no experimental role there. This is a verified full-text contradiction (not an abstract-only inference), so REMOVE is warranted; flagged for curator re-assignment to the paralog mid2. |
| GO:0071341 medial cortical node | IDA PMID:19474789 A spatial gradient coordinates cell size and mitotic entry i... | ACCEPT | Summary: Mid1 is a documented component of medial cortical nodes that also contain Wee1, Cdr1 and Cdr2. Directly observed. Core localization. Reason: Direct evidence for Mid1 in interphase medial cortical nodes. Supporting Evidence: PMID:19474789 This network is located at cortical nodes in the middle of interphase cells, and these nodes contain the Cdk1 inhibitor Wee1, the Wee1-inhibitory kinases Cdr1 (also known as Nim1) and Cdr2, and the anillin-like protein Mid1. |
| GO:0005515 protein binding | IPI PMID:18378776 The Clp1/Cdc14 phosphatase contributes to the robustness of ... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" with interactor PomBase:SPAC1782.09c (Clp1/Flp1). The meaningful relationship is that Mid1 tethers the Clp1/Cdc14 phosphatase at the contractile ring via its scaffold function; the generic MF term is uninformative. Reason: Generic protein binding term is uninformative; Mid1's scaffolding/anchor activity is captured by GO:0043495 and GO:0140693. Supporting Evidence: PMID:18378776 Clp1/Flp1 is tethered at the contractile ring (CR) through its association with anillin-related Mid1. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:18378776 The Clp1/Cdc14 phosphatase contributes to the robustness of ... | ACCEPT | Summary: Mid1 is anchored at the cell midzone/contractile ring and serves as a scaffold tethering Clp1. Direct FRAP-based evidence that Mid1 is stably anchored in the ring. Core localization. Reason: Direct evidence (FRAP) for Mid1 anchored at the contractile ring/midzone. Supporting Evidence: PMID:18378776 Mid1, unlike other tested CR components, is anchored at the cell midzone, and this physical property is likely to account for its scaffolding role. |
| GO:0071341 medial cortical node | IDA PMID:24790095 Characterization of the roles of Blt1p in fission yeast cyto... | ACCEPT | Summary: Mid1 is present in interphase/cytokinetic nodes together with Blt1; this study of Blt1 documents Mid1 node localization. Directly observed. Core localization. Reason: Direct imaging of Mid1 in cortical nodes in the context of Blt1 function. Supporting Evidence: PMID:24790095 proteins that contribute to the cytokinetic contractile ring accumulate during interphase in nodes-precursor structures around the equatorial cortex. |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:24790095 Characterization of the roles of Blt1p in fission yeast cyto... | ACCEPT | Summary: Mid1-containing nodes condense into the contractile ring; Mid1 is a ring component during assembly. Directly observed. Core localization. Reason: Direct imaging places Mid1 in nodes that condense to the ring. Supporting Evidence: PMID:24790095 During mitosis, additional proteins join these nodes, which condense to form the contractile ring. |
| GO:0090488 polo box domain specific binding | IPI PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | ACCEPT | Summary: Mid1 interacts with polo kinase Plo1 (PomBase:SPAC23C11.16), which acts in a common pathway with Mid1 and is required for Mid1 nuclear exit and ring formation. Mid1 is phosphorylated by Cdk1 to create a polo-box docking site, supporting specific polo-box-domain binding. This is an informative, specific molecular function. Reason: Two-hybrid and genetic data support a specific Mid1-Plo1 (polo box) interaction central to regulation of Mid1. Supporting Evidence: PMID:9852154 Genetic and two-hybrid analyses suggest that Plo1p and Mid1p act in a common pathway distinct from that involving Pom1p. |
| GO:0005515 protein binding | IPI PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | MARK AS OVER ANNOTATED | Summary: Bare "protein binding" with interactor Plo1 (PomBase:SPAC23C11.16). This is redundant with, and less informative than, the specific polo-box-domain binding annotation from the same paper. Reason: Uninformative generic term, redundant with the specific GO:0090488 annotation for the same Plo1 interaction. Supporting Evidence: PMID:9852154 Genetic and two-hybrid analyses suggest that Plo1p and Mid1p act in a common pathway distinct from that involving Pom1p. |
| GO:0005634 nucleus | IDA PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | ACCEPT | Summary: Mid1 is nuclear during interphase and requires Plo1 for nuclear exit; nuclear localization directly observed. Accept. Reason: Direct evidence for the nuclear Mid1 pool; Plo1 controls its export. Supporting Evidence: PMID:9852154 Plo1p is required for Mid1p to exit the nucleus and form a ring |
| GO:0110085 mitotic actomyosin contractile ring | IDA PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | ACCEPT | Summary: Mid1 coalesces into the medial ring (contractile ring) before anaphase; directly observed. Core localization. Reason: Direct imaging of Mid1 forming the medial contractile ring. Supporting Evidence: PMID:9852154 Mid1p first forms a diffuse cortical band during spindle formation and then coalesces into a ring before anaphase. |
| GO:1903475 mitotic actomyosin contractile ring assembly | IMP PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | ACCEPT | Summary: mid1 mutants show defective placement and organization of the medial ring, with ring formation initiating near cell poles; Mid1 functions in recruiting ring components to the cell center. Core function, supported by mutant phenotype. Reason: Mutant-phenotype evidence for Mid1 in contractile ring assembly/placement. Supporting Evidence: PMID:9852154 ring formation is frequently initiated near the cell poles, indicating that Mid1p and Plo1p function in recruiting medial ring components to the cell center. |
| GO:1902408 mitotic cytokinesis, division site positioning | IMP PMID:9852154 Role of polo kinase and Mid1p in determining the site of cel... | ACCEPT | Summary: mid1 mutants mis-place the division site, demonstrating Mid1's role in positioning the cell-division site. Core function, supported by mutant phenotype. Reason: Mutant-phenotype evidence for division-site positioning. Supporting Evidence: PMID:9852154 the data indicate that Plo1p plays a role in the positioning of division sites by regulating Mid1p. |
| GO:0031097 medial cortex | IDA PMID:20870879 Reorganization of the growth pattern of Schizosaccharomyces ... | ACCEPT | Summary: In a survey of polarity/division proteins during invasive filament growth, Mid1 localizes similarly in filaments and single cells (medial cortex). This is a high-content localization study; medial cortex localization is consistent with all prior data. Reason: Consistent with established medial cortex localization of Mid1. Supporting Evidence: PMID:20870879 A third group acting at different stages of the cell cycle, including Bud6, Rga4, and Mid1, localize similarly in filaments and single cells |
| GO:0005635 nuclear envelope | HDA PMID:16823372 ORFeome cloning and global analysis of protein localization ... | KEEP AS NON CORE | Summary: This high-throughput ORFeome localization study (HDA) assigned a nuclear envelope signal. Mid1's robust, focused experimental data place it in the nucleoplasm/nucleus during interphase and at the medial cortex/ring; nuclear-envelope as a distinct functional compartment is not supported by focused studies and is likely a coarse high-throughput call reflecting the nuclear pool. Best kept as non-core pending verification. Reason: Single high-throughput annotation; the nuclear-envelope signal probably reflects the well-documented nuclear pool rather than a specific nuclear-envelope function. Retain as non-core, not as a core localization. Supporting Evidence: PMID:8946912 In wild-type cells, Dmf1p is nuclear during interphase |
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Download this section (compressed HTML)Q: How do nuclear export (CRM1/NES-dependent) and Cdr2-dependent cortical anchoring quantitatively combine to read out nuclear position and translate it into division-plane position?
Q: What is the precise contribution of Mid1 phase separation versus stoichiometric protein-protein interactions to node formation and stability in vivo?
Experiment: Optogenetic or chemically inducible control of Mid1 nuclear export to test, in real time, whether acute relocalization of Mid1 to defined cortical zones is sufficient to redirect the division plane.
Experiment: Reconstitute Mid1 (full-length and N-terminal disordered fragment) with PI(4,5)P2-containing supported lipid bilayers and purified Myo2/Rng2/Cdc15 to measure how phase separation and membrane binding cooperate to recruit ring components.
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