mhcA

id: P08799
gene_symbol: mhcA
product_type: PROTEIN
status: COMPLETE
taxon:
  id: NCBITaxon:44689
  label: Dictyostelium discoideum
description: >-
  mhcA encodes the single conventional (class II) myosin heavy chain of
  Dictyostelium discoideum, the ~243 kDa force-generating subunit of non-muscle
  myosin II. Each heavy chain has an N-terminal globular motor (head) domain that
  binds actin and hydrolyzes ATP, a neck/IQ region that binds the essential and
  regulatory light chains, and a long alpha-helical coiled-coil tail. Two heavy
  chains dimerize through their tails and, together with two essential and two
  regulatory light chains, form the two-headed myosin II hexamer, which
  self-assembles tail-to-tail into bipolar thick filaments. Filament assembly is
  regulated by phosphorylation of three C-terminal tail threonines (Thr1823,
  Thr1833, Thr2029) by myosin heavy chain kinases, which drives disassembly. As an
  actin-activated ATPase motor, myosin II slides antiparallel actin filaments to
  generate contractile force at the cell cortex. It is concentrated in the
  posterior/rear cortex of migrating cells and in the equatorial cortex/cleavage
  furrow of dividing cells, where its contractility is essential for cytokinesis
  (myosin-null cells fail to divide in suspension and become large and
  multinucleate), for generating and maintaining three-dimensional cell shape and
  cortical tension, for tail/uropod and pseudopod retraction during chemotactic
  migration, for bleb-based motility, and for multicellular morphogenesis
  (culmination and fruiting body/sorocarp formation). Myosin II also acts as part
  of a cortical mechanosensor that couples mechanical stress to its own
  accumulation, and contributes to contractile-vacuole discharge and cortical
  dynamics during phagocytosis.
existing_annotations:
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Phylogenetic inference that myosin II acts in the cytoplasm. Correct
      and well supported by direct evidence, though not the most informative
      localization for this cortical motor.
    action: ACCEPT
    reason: Myosin II is a cytoplasmic/cortical protein; the general cytoplasm term
      is correct but subordinate to the more specific cell cortex and cleavage
      furrow localizations captured elsewhere.
    supported_by:
    - reference_id: PMID:2578450
      supporting_text: If ATP is present, 98% of that myosin is released
- term:
    id: GO:0000146
    label: microfilament motor activity
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: Phylogenetic inference of actin-based motor activity, the defining
      molecular function of a conventional myosin heavy chain.
    action: ACCEPT
    reason: Directly demonstrated for the Dictyostelium myosin II head, which is an
      actin-activated ATPase that supports actin filament sliding. This is a core
      molecular function.
    supported_by:
    - reference_id: PMID:2530629
      supporting_text: displayed actin-activated adenosine triphosphatase activity
- term:
    id: GO:0051015
    label: actin filament binding
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: enables
  review:
    summary: Phylogenetic inference of actin filament binding, an integral part of
      the myosin motor cycle.
    action: ACCEPT
    reason: The Dictyostelium myosin II motor domain binds actin filaments directly;
      loop-4 and cleft mutations that weaken actin binding have been characterized.
      Core function.
    supported_by:
    - reference_id: PMID:18067324
      supporting_text: loop 4 is a functional actin-binding region that stabilizes
        actomyosin
- term:
    id: GO:0016460
    label: myosin II complex
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: part_of
  review:
    summary: Phylogenetic inference that the heavy chain is part of the myosin II
      hexameric complex.
    action: ACCEPT
    reason: mhcA is the heavy chain of the two-headed myosin II hexamer (2 heavy, 2
      essential and 2 regulatory light chains). Core assignment.
    supported_by:
    - reference_id: PMID:15492777
      supporting_text: forms bipolar thick filament (BTF) structures
- term:
    id: GO:0032982
    label: myosin filament
  evidence_type: IBA
  original_reference_id: GO_REF:0000033
  qualifier: is_active_in
  review:
    summary: Phylogenetic inference that myosin II is active in myosin (thick)
      filaments.
    action: ACCEPT
    reason: Myosin II self-assembles into bipolar thick filaments that are the
      functional force-generating unit. Core assignment.
    supported_by:
    - reference_id: PMID:15492777
      supporting_text: assembles in a regulated manner similar to full-length
        myosin-II and
- term:
    id: GO:0003774
    label: cytoskeletal motor activity
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO inference of cytoskeletal motor activity from the myosin
      motor domain.
    action: ACCEPT
    reason: Parent term of microfilament motor activity; correct for the actin-based
      myosin II motor.
    supported_by:
    - reference_id: PMID:2530629
      supporting_text: displayed actin-activated adenosine triphosphatase activity
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO inference of ATP binding from the P-loop of the myosin
      motor domain.
    action: ACCEPT
    reason: The myosin motor domain has a canonical ATP-binding P-loop and
      hydrolyzes ATP to power the motor. Core function.
    supported_by:
    - reference_id: PMID:2530629
      supporting_text: displayed actin-activated adenosine triphosphatase activity
- term:
    id: GO:0005737
    label: cytoplasm
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: located_in
  review:
    summary: ARBA electronic annotation of cytoplasmic localization. Correct.
    action: ACCEPT
    reason: Myosin II is cytoplasmic/cortical; consistent with direct evidence.
    supported_by:
    - reference_id: PMID:2578450
      supporting_text: contain nearly half of the cell's myosin
- term:
    id: GO:0005938
    label: cell cortex
  evidence_type: IEA
  original_reference_id: GO_REF:0000044
  qualifier: located_in
  review:
    summary: UniProt subcellular-location electronic annotation of cell cortex
      localization, matching the documented enrichment in the posterior cortex.
    action: ACCEPT
    reason: Myosin II is highly enriched in the cell cortex, particularly the
      posterior cortex of migrating cells. Core localization.
    supported_by:
    - reference_id: PMID:16461463
      supporting_text: Highly enriched in the cell cortex, actin, myosin II
- term:
    id: GO:0016459
    label: myosin complex
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: part_of
  review:
    summary: InterPro2GO inference that the heavy chain is part of a myosin complex.
    action: ACCEPT
    reason: Correct but general; the more specific myosin II complex is the accurate
      assignment for this class II heavy chain.
    supported_by:
    - reference_id: PMID:15492777
      supporting_text: forms bipolar thick filament (BTF) structures
- term:
    id: GO:0031143
    label: pseudopodium
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: located_in
  review:
    summary: ARBA electronic annotation of pseudopodium localization, corroborated
      by live-imaging showing transient myosin enrichment in retracting pseudopods.
    action: KEEP_AS_NON_CORE
    reason: Myosin II transiently concentrates in the tips of retracting pseudopods,
      but its predominant and functionally central localization is the posterior
      cortex and cleavage furrow.
    supported_by:
    - reference_id: PMID:8552657
      supporting_text: increases transiently in the tips of retracting pseudopods
- term:
    id: GO:0031152
    label: aggregation involved in sorocarp development
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: ARBA electronic annotation of a role in aggregation. Myosin-null cells
      still aggregate, so involvement in the aggregation step itself is
      overstated by this electronic inference.
    action: MARK_AS_OVER_ANNOTATED
    reason: Genetic ablation of mhcA blocks development at a later (post-aggregation)
      stage; myosin-null (hmm) cells can still aggregate. The requirement is at
      culmination, not aggregation, so annotation to the aggregation step
      over-reaches.
    supported_by:
    - reference_id: PMID:3576222
      supporting_text: blocked at a later stage in the Dictyostelium
- term:
    id: GO:0031270
    label: pseudopodium retraction
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: ARBA electronic annotation of a role in pseudopodium retraction,
      supported experimentally by traction-force imaging of retracting pseudopods.
    action: ACCEPT
    reason: Accumulated filamentous myosin II generates the contractile force that
      retracts pseudopodia and the cell rear during migration.
    supported_by:
    - reference_id: PMID:18388319
      supporting_text: the source of the retraction force is the motor activity of
        accumulated myosin
- term:
    id: GO:0048870
    label: cell motility
  evidence_type: IEA
  original_reference_id: GO_REF:0000117
  qualifier: involved_in
  review:
    summary: ARBA electronic annotation of a role in cell motility.
    action: KEEP_AS_NON_CORE
    reason: Myosin II contributes to amoeboid motility (rear retraction, cortical
      tension, bleb-based movement) but is not strictly required for all forms of
      locomotion; it is a modulator rather than the propulsive engine.
    supported_by:
    - reference_id: PMID:25887420
      supporting_text: the cytoskeletal genes abpA or mhcA, which are also required
        for motility
- term:
    id: GO:0051015
    label: actin filament binding
  evidence_type: IEA
  original_reference_id: GO_REF:0000002
  qualifier: enables
  review:
    summary: InterPro2GO inference of actin filament binding from the myosin motor
      domain. Consistent with direct biochemical evidence.
    action: ACCEPT
    reason: The myosin II motor domain binds actin filaments directly. Core
      function.
    supported_by:
    - reference_id: PMID:18067324
      supporting_text: loop 4 is a functional actin-binding region that stabilizes
        actomyosin
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18725645
  qualifier: enables
  review:
    summary: Bare protein binding from an EPR/spin-labeling study of the myosin
      actin-binding cleft. Uninformative term; the interaction assayed is
      myosin-actin.
    action: KEEP_AS_NON_CORE
    reason: The generic protein binding term conveys little; the underlying
      interaction is actin binding by the myosin motor, already captured by the
      actin filament binding annotations.
    supported_by:
    - reference_id: PMID:18725645
      supporting_text: closure of the actin-binding cleft of myosin
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18854143
  qualifier: enables
  review:
    summary: Protein binding reflecting the physical association of myosin II with
      the Elmo-like protein ElmoA at the cortex.
    action: KEEP_AS_NON_CORE
    reason: A real interaction (ElmoA associates with cortical actin and myosin II)
      but the bare protein binding term is uninformative; the specific partner is
      noted here.
    supported_by:
    - reference_id: PMID:18854143
      supporting_text: ElmoA associates with cortical actin and myosin II
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18971336
  qualifier: enables
  review:
    summary: Protein binding derived from a genetically-encoded strain sensor
      visualizing the myosin II-F-actin interaction.
    action: KEEP_AS_NON_CORE
    reason: The interaction assayed is myosin-actin, already captured by actin
      filament binding; the generic protein binding term adds no specific
      information.
    supported_by:
    - reference_id: PMID:18971336
      supporting_text: visualize the interaction between myosin II and F-actin in
        Dictyostelium cells
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:20351242
  qualifier: enables
  review:
    summary: Protein binding from a biophysical study of the myosin.ADP.blebbistatin
      complex probing actin binding and lever priming.
    action: KEEP_AS_NON_CORE
    reason: The assayed interaction is myosin-actin under a pharmacological probe;
      the bare protein binding term is uninformative and subordinate to the
      actin-binding and motor annotations.
    supported_by:
    - reference_id: PMID:20351242
      supporting_text: blebbistatin does not weaken the tight actin binding of myosin
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:15492777
  qualifier: enables
  review:
    summary: Self-association of myosin heavy chains through tail-tail interactions
      to build bipolar thick filaments.
    action: ACCEPT
    reason: Myosin II self-assembles into bipolar thick filaments via homotypic
      coiled-coil tail interactions; identical protein binding captures this core
      self-assembly activity.
    supported_by:
    - reference_id: PMID:15492777
      supporting_text: forms bipolar thick filament (BTF) structures
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:41353402
  qualifier: enables
  review:
    summary: Protein binding annotation arising from a study of talin-A force
      coupling in amoeboid cells. The abstract does not detail a direct
      myosin-partner interaction, and full text was not verified here.
    action: UNDECIDED
    reason: Cannot verify the specific myosin II interaction claimed from the
      available text; the paper focuses on talin/SibA force coupling. Per policy,
      an unverifiable experimental interaction is left undecided rather than
      accepted or removed.
- term:
    id: GO:0044351
    label: macropinocytosis
  evidence_type: IMP
  original_reference_id: PMID:41332277
  qualifier: acts_upstream_of_or_within
  review:
    summary: Myosin II is a component of cytoplasmic contractility kits whose loss
      affects cell mechanics and macropinocytosis-related processes.
    action: KEEP_AS_NON_CORE
    reason: Myosin II contributes to cortical mechanics underlying macropinocytic
      cup dynamics, but macropinocytosis is a downstream cellular process rather
      than the core motor function.
    supported_by:
    - reference_id: PMID:41332277
      supporting_text: myosin II, cortexillin I and IQGAP1 assemble in the cytoplasm
        into
- term:
    id: GO:0140350
    label: inchworm-type cell migration
  evidence_type: IMP
  original_reference_id: PMID:40712579
  qualifier: acts_upstream_of_or_within
  review:
    summary: On highly adhesive surfaces Dictyostelium switches to inchworm
      migration that repurposes the cytokinesis (actomyosin) machinery, of which
      myosin II is central.
    action: KEEP_AS_NON_CORE
    reason: Myosin II-based contractility is redeployed for this specialized
      migration mode; it is a context-specific behavior rather than a core
      molecular function.
    supported_by:
    - reference_id: PMID:40712579
      supporting_text: the repurposing of cytokinesis machinery for migration mode
        shifting
- term:
    id: GO:0000915
    label: actomyosin contractile ring assembly
  evidence_type: IMP
  original_reference_id: PMID:40712579
  qualifier: acts_upstream_of_or_within
  review:
    summary: Assembly of the contractile actomyosin ring/machinery, which
      incorporates myosin II, is invoked during inchworm migration and cytokinesis.
    action: KEEP_AS_NON_CORE
    reason: Myosin II is a required component of the actomyosin contractile ring;
      here the term is applied in the migration context. Genuine but secondary to
      the cytokinesis role captured by the core function.
    supported_by:
    - reference_id: PMID:40712579
      supporting_text: the repurposing of cytokinesis machinery for migration mode
        shifting
- term:
    id: GO:0001931
    label: uropod
  evidence_type: IDA
  original_reference_id: PMID:17126332
  qualifier: is_active_in
  review:
    summary: Filamentous myosin II is recruited to the rear (tail/uropod) of
      chemotaxing cells.
    action: ACCEPT
    reason: The cell tail is specified by recruitment of filamentous myosin-II;
      uropod localization is well documented and functionally important for rear
      retraction.
    supported_by:
    - reference_id: PMID:17126332
      supporting_text: the tail by the recruitment of filamentous myosin-II
- term:
    id: GO:0000281
    label: mitotic cytokinesis
  evidence_type: IMP
  original_reference_id: PMID:10588668
  qualifier: involved_in
  review:
    summary: Myosin II localizes to the cleavage furrow and is required for
      furrow-based cytokinesis; studied here in the context of the LvsA cytokinesis
      mutant.
    action: ACCEPT
    reason: Myosin II accumulation at the cleavage furrow drives the contractile
      ring; this is a core cellular role of mhcA.
    supported_by:
    - reference_id: PMID:10588668
      supporting_text: they initiate furrow formation with concomitant myosin II
        localization at the
- term:
    id: GO:0000281
    label: mitotic cytokinesis
  evidence_type: IGI
  original_reference_id: PMID:19065153
  qualifier: involved_in
  review:
    summary: Genetic interaction showing mhcA (myosin II) contributes to
      contractile-ring-dependent cytokinesis, with adhesion molecules covering a
      parallel ring-independent pathway.
    action: ACCEPT
    reason: Double knockouts of mhcA with paxB or vinA have more severe cytokinesis
      defects, confirming myosin II's role in furrow-based division. Core role.
    supported_by:
    - reference_id: PMID:19065153
      supporting_text: Double knockout strains lacking mhcA, which codes for myosin
        II
- term:
    id: GO:0000281
    label: mitotic cytokinesis
  evidence_type: IMP
  original_reference_id: PMID:2721503
  qualifier: involved_in
  review:
    summary: Myosin-null mutants generated by gene replacement fail normal cell
      division in suspension, providing genetic proof of the cytokinesis
      requirement.
    action: ACCEPT
    reason: Elimination of the conventional myosin gene abolishes normal cell
      division in suspension. Core cellular role.
    supported_by:
    - reference_id: PMID:2721503
      supporting_text: the conventional myosin gene is required for growth in
        suspension, normal
- term:
    id: GO:0000281
    label: mitotic cytokinesis
  evidence_type: IMP
  original_reference_id: PMID:3576222
  qualifier: involved_in
  review:
    summary: Disruption of the myosin heavy chain gene produces multinucleate cells
      defective in cytokinesis, the classic genetic proof of myosin II's role.
    action: ACCEPT
    reason: hmm cells defective in cytokinesis become large and multinucleate;
      genetic proof that intact myosin is required for cytokinesis. Core role.
    supported_by:
    - reference_id: PMID:3576222
      supporting_text: genetic proof that the intact myosin molecule is required for
        cytokinesis
- term:
    id: GO:0006930
    label: substrate-dependent cell migration, cell extension
  evidence_type: IDA
  original_reference_id: PMID:37987147
  qualifier: involved_in
  review:
    summary: Amoeboid migration/pathfinding involving nucleokinesis; myosin II
      contributes to the contractile forces that reposition the cell body and
      nucleus.
    action: KEEP_AS_NON_CORE
    reason: Myosin II-driven cortical contractility participates in amoeboid
      migration and cell extension/retraction, but this migratory behavior is
      downstream of the core motor function.
    supported_by:
    - reference_id: PMID:18388319
      supporting_text: the source of the retraction force is the motor activity of
        accumulated myosin
- term:
    id: GO:0006935
    label: chemotaxis
  evidence_type: IMP
  original_reference_id: PMID:16926192
  qualifier: involved_in
  review:
    summary: Myosin II is required for bleb-based leading-edge protrusion and rear
      retraction that contribute to efficient chemotactic movement.
    action: KEEP_AS_NON_CORE
    reason: Myosin II contributes to chemotactic locomotion (bleb formation, cell
      body retraction), but chemotaxis is an integrated cellular behavior rather
      than the core molecular function.
    supported_by:
    - reference_id: PMID:16926192
      supporting_text: reduced under conditions that prevent blebbing
- term:
    id: GO:0008360
    label: regulation of cell shape
  evidence_type: IMP
  original_reference_id: PMID:8874966
  qualifier: involved_in
  review:
    summary: Myosin II is required for generating and maintaining three-dimensional
      cell shape independent of the substrate.
    action: ACCEPT
    reason: Cells lacking myosin II cannot generate or maintain 3D shape and become
      spherical in suspension; cortical-tension-based shape control is a central
      myosin II function.
    supported_by:
    - reference_id: PMID:8874966
      supporting_text: 3D cell shape generation requires myosin II
- term:
    id: GO:0009612
    label: response to mechanical stimulus
  evidence_type: IMP
  original_reference_id: PMID:23442953
  qualifier: involved_in
  review:
    summary: Myosin II accumulates at sites of mechanical strain during cyclic
      substrate stretching, mediating directional responses.
    action: KEEP_AS_NON_CORE
    reason: Myosin II participates in the cellular response to mechanical stimuli by
      accumulating where strain is received; this mechanoresponsive behavior is
      secondary to its motor/contractile function.
    supported_by:
    - reference_id: PMID:23442953
      supporting_text: Dictyostelium cells accumulate myosin II at the portion of
        the cell where a
- term:
    id: GO:0030038
    label: contractile actin filament bundle assembly
  evidence_type: IMP
  original_reference_id: PMID:15894626
  qualifier: involved_in
  review:
    summary: This paper analyzes subsecond actin-network reorganization and bundle
      formation but does not, in the available abstract, establish a myosin II
      requirement; full text was not verified.
    action: UNDECIDED
    reason: The cited abstract concerns actin filament growth and bundling dynamics
      and does not describe a myosin II perturbation. Unable to verify the basis of
      this annotation from available text.
- term:
    id: GO:0030837
    label: negative regulation of actin filament polymerization
  evidence_type: IMP
  original_reference_id: PMID:15894626
  qualifier: involved_in
  review:
    summary: A role for myosin II in negatively regulating actin polymerization is
      not established by the available abstract, which focuses on actin-network
      dynamics.
    action: UNDECIDED
    reason: Cannot verify a myosin II perturbation or a direct role in limiting
      actin polymerization from the cited text; left undecided per policy.
- term:
    id: GO:0031152
    label: aggregation involved in sorocarp development
  evidence_type: IEP
  original_reference_id: PMID:25887420
  qualifier: involved_in
  review:
    summary: Expression-based association; mhcA is a cytoskeletal gene differentially
      regulated during development. Myosin-null cells nonetheless still aggregate,
      so involvement in the aggregation step is overstated.
    action: MARK_AS_OVER_ANNOTATED
    reason: IEP reflects developmental expression rather than a specific requirement
      for aggregation; myosin-null cells still aggregate and are blocked later, at
      culmination. Annotation to the aggregation step over-reaches.
    supported_by:
    - reference_id: PMID:25887420
      supporting_text: the cytoskeletal genes abpA or mhcA, which are also required
        for motility
- term:
    id: GO:0031154
    label: culmination involved in sorocarp development
  evidence_type: IMP
  original_reference_id: PMID:2721503
  qualifier: involved_in
  review:
    summary: Myosin-null mutants are defective in later multicellular development
      (sporogenesis), consistent with a requirement at culmination.
    action: ACCEPT
    reason: The conventional myosin gene is required for sporogenesis; myosin II
      contractility is needed for the morphogenetic cell movements of culmination.
    supported_by:
    - reference_id: PMID:2721503
      supporting_text: cell division and sporogenesis
- term:
    id: GO:0031154
    label: culmination involved in sorocarp development
  evidence_type: IMP
  original_reference_id: PMID:3576222
  qualifier: involved_in
  review:
    summary: Myosin heavy chain disruption blocks development at a late stage after
      aggregation, consistent with a culmination defect.
    action: ACCEPT
    reason: hmm (myosin-null) cells aggregate but are blocked later in the
      developmental cycle, indicating a requirement in culmination/morphogenesis.
    supported_by:
    - reference_id: PMID:3576222
      supporting_text: blocked at a later stage in the Dictyostelium
- term:
    id: GO:0031270
    label: pseudopodium retraction
  evidence_type: IMP
  original_reference_id: PMID:18388319
  qualifier: involved_in
  review:
    summary: Motor activity of accumulated filamentous myosin II generates the
      contractile forces that retract pseudopodia.
    action: ACCEPT
    reason: Direct force-microscopy evidence that myosin II motor activity is the
      source of retraction force in pseudopodia; a central role in rear/tail
      dynamics during migration.
    supported_by:
    - reference_id: PMID:18388319
      supporting_text: the source of the retraction force is the motor activity of
        accumulated myosin
- term:
    id: GO:0033298
    label: contractile vacuole organization
  evidence_type: IMP
  original_reference_id: PMID:19843280
  qualifier: involved_in
  review:
    summary: The cortical myosin II cytoskeleton contributes to periodic
      contractions and discharge of the contractile vacuole; myosin-null cells have
      enlarged, dysfunctional vacuoles.
    action: KEEP_AS_NON_CORE
    reason: Myosin II supports contractile-vacuole dynamics as part of its general
      cortical contractile role; a legitimate but non-core cellular function.
    supported_by:
    - reference_id: PMID:19843280
      supporting_text: myosin II null cells also results in enlarged CVs with
        impaired dynamics
- term:
    id: GO:0034461
    label: uropod retraction
  evidence_type: IMP
  original_reference_id: PMID:18388319
  qualifier: involved_in
  review:
    summary: Accumulated myosin II generates the contractile traction that retracts
      the cell rear/uropod during migration.
    action: ACCEPT
    reason: Myosin II motor activity provides the rear-retraction force documented
      by simultaneous imaging of GFP-myosin II and traction forces. Core migratory
      role.
    supported_by:
    - reference_id: PMID:18388319
      supporting_text: the source of the retraction force is the motor activity of
        accumulated myosin
- term:
    id: GO:0046847
    label: filopodium assembly
  evidence_type: IMP
  original_reference_id: PMID:15855234
  qualifier: involved_in
  review:
    summary: Myosin II heavy chain phosphorylation state modulates filopod formation
      during migration and chemotaxis.
    action: KEEP_AS_NON_CORE
    reason: Regulated myosin II (via MHC phosphorylation) influences filopod
      formation, but filopodium assembly is primarily an actin-driven process that
      myosin II modulates rather than directly executes.
    supported_by:
    - reference_id: PMID:15855234
      supporting_text: MHC phosphorylation-dephosphorylation plays a role in the
        regulation of filopod
- term:
    id: GO:0050982
    label: detection of mechanical stimulus
  evidence_type: IMP
  original_reference_id: PMID:22379107
  qualifier: involved_in
  review:
    summary: Myosin II, together with cortexillin I, forms the core cortical
      mechanosensor that detects and responds to mechanical stress.
    action: ACCEPT
    reason: Myosin II is a direct constituent of the mechanosensory module that
      accumulates in response to applied mechanical stress; mechanosensation is an
      established myosin II activity in this organism.
    supported_by:
    - reference_id: PMID:22379107
      supporting_text: the mechanoenzyme myosin II and the actin cross-linker
        cortexillin I form a
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:36165849
  qualifier: enables
  review:
    summary: Protein binding reflecting myosin II's participation in cytoplasmic
      contractility kits alongside Discoidin I, cortexillin I and IQGAP.
    action: KEEP_AS_NON_CORE
    reason: A real assembly-level interaction, but the generic protein binding term
      is uninformative; the specific contractility-kit context is noted here.
    supported_by:
    - reference_id: PMID:36165849
      supporting_text: the contractility machinery organizes into higher order
        assemblies termed
- term:
    id: GO:0140220
    label: pathogen-containing vacuole
  evidence_type: HDA
  original_reference_id: PMID:18980612
  qualifier: part_of
  review:
    summary: Myosin II was detected among hundreds of host proteins in a proteomic
      analysis of purified Legionella-containing vacuoles.
    action: KEEP_AS_NON_CORE
    reason: Detection in a whole-vacuole proteome likely reflects cortical/cytoplasmic
      myosin II associated with the phagosomal membrane rather than a dedicated
      vacuolar function; retained as non-core, peripheral association.
    supported_by:
    - reference_id: PMID:18980612
      supporting_text: revealed 566 host proteins
- term:
    id: GO:0000146
    label: microfilament motor activity
  evidence_type: IDA
  original_reference_id: PMID:2530629
  qualifier: enables
  review:
    summary: The isolated recombinant myosin head fragment displays actin-activated
      ATPase activity and supports actin filament sliding in vitro.
    action: ACCEPT
    reason: Direct demonstration of the core actin-based motor activity of the
      Dictyostelium myosin II head.
    supported_by:
    - reference_id: PMID:2530629
      supporting_text: displayed actin-activated adenosine triphosphatase activity
- term:
    id: GO:0005829
    label: cytosol
  evidence_type: IDA
  original_reference_id: PMID:23132928
  qualifier: located_in
  review:
    summary: Myosin II is present in the cytosol (soluble/disassembled pool), from
      which it assembles onto the cortex.
    action: ACCEPT
    reason: A substantial fraction of myosin II is soluble/cytosolic and is released
      from the cytoskeleton in the presence of ATP; cytosolic localization is
      correct though subordinate to cortical localization.
    supported_by:
    - reference_id: PMID:2578450
      supporting_text: If ATP is present, 98% of that myosin is released
- term:
    id: GO:0016460
    label: myosin II complex
  evidence_type: IDA
  original_reference_id: PMID:4278009
  qualifier: part_of
  review:
    summary: Classic biochemical isolation and characterization of Dictyostelium
      myosin, establishing the actomyosin-like myosin II complex.
    action: ACCEPT
    reason: The heavy chain is the core subunit of the isolated myosin II complex.
    supported_by:
    - reference_id: PMID:4278009
      supporting_text: Isolation and characterization of myosin from amoebae of
        Dictyostelium
- term:
    id: GO:0031012
    label: extracellular matrix
  evidence_type: HDA
  original_reference_id: PMID:26152465
  qualifier: located_in
  review:
    summary: Myosin II was identified in a proteomic profile of the slug
      extracellular matrix (slime sheath).
    action: MARK_AS_OVER_ANNOTATED
    reason: Myosin II is an intracellular cortical motor; its detection in a
      slime-sheath proteome most likely reflects cytoplasmic contamination during
      ECM preparation rather than a genuine extracellular-matrix localization.
    supported_by:
    - reference_id: PMID:26152465
      supporting_text: An LC/MS/MS analysis of slug ECM revealed the presence of a
        large number of
- term:
    id: GO:0031143
    label: pseudopodium
  evidence_type: IDA
  original_reference_id: PMID:8552657
  qualifier: is_active_in
  review:
    summary: Live-cell GFP-myosin imaging shows transient myosin II enrichment in
      the tips of retracting pseudopods.
    action: KEEP_AS_NON_CORE
    reason: Genuine but transient localization; myosin II's principal functional
      sites are the posterior cortex and cleavage furrow.
    supported_by:
    - reference_id: PMID:8552657
      supporting_text: increases transiently in the tips of retracting pseudopods
- term:
    id: GO:0031254
    label: cell trailing edge
  evidence_type: IDA
  original_reference_id: PMID:22114350
  qualifier: is_active_in
  review:
    summary: Myosin II is enriched at the rear/trailing edge (posterior cortex) of
      migrating cells.
    action: ACCEPT
    reason: Posterior/trailing-edge enrichment of myosin II is a hallmark of its
      role in rear retraction during directed migration.
    supported_by:
    - reference_id: PMID:8552657
      supporting_text: posterior cortex of migrating cells
- term:
    id: GO:0031410
    label: cytoplasmic vesicle
  evidence_type: IDA
  original_reference_id: PMID:3243031
  qualifier: located_in
  review:
    summary: Immuno-EM localizes a fraction of myosin II to unidentified cytoplasmic
      vesicles in addition to cortical filament arrays.
    action: KEEP_AS_NON_CORE
    reason: A minor documented localization; peripheral to the core cortical
      contractile function.
    supported_by:
    - reference_id: PMID:3243031
      supporting_text: with unidentified cytoplasmic vesicles
- term:
    id: GO:0032009
    label: early phagosome
  evidence_type: IDA
  original_reference_id: PMID:20200225
  qualifier: located_in
  review:
    summary: Myosin II is part of the concentric protein rings of the phagocytic
      furrow/cup during particle engulfment.
    action: KEEP_AS_NON_CORE
    reason: Myosin II localizes to the phagocytic furrow together with MyoK, Abp1,
      Arp3 and coronin; a genuine but non-core localization reflecting cortical
      contractility during phagocytosis.
    supported_by:
    - reference_id: PMID:20200225
      supporting_text: concentric overlapping rings of MyoK, Abp1, Arp3, coronin,
        and myosin II
- term:
    id: GO:0032154
    label: cleavage furrow
  evidence_type: IDA
  original_reference_id: PMID:19515202
  qualifier: is_active_in
  review:
    summary: Myosin II co-localizes with PTEN at the furrow region of dividing
      cells.
    action: ACCEPT
    reason: Cleavage-furrow localization of myosin II is central to its cytokinesis
      function. Core localization.
    supported_by:
    - reference_id: PMID:19515202
      supporting_text: region of dividing cells
- term:
    id: GO:0032154
    label: cleavage furrow
  evidence_type: IDA
  original_reference_id: PMID:8552657
  qualifier: is_active_in
  review:
    summary: GFP-myosin concentrates in the cleavage furrow during cytokinesis in
      live cells.
    action: ACCEPT
    reason: Direct live-cell evidence of myosin II furrow localization during
      division. Core localization.
    supported_by:
    - reference_id: PMID:8552657
      supporting_text: GFP-myosin is concentrated in the cleavage furrow during
        cytokinesis and in the
- term:
    id: GO:0097204
    label: phagocytic cup base
  evidence_type: IDA
  original_reference_id: PMID:12952073
  qualifier: located_in
  review:
    summary: Myosin II localizes to the base of phagocytic cups and the rear of
      locomoting cells.
    action: KEEP_AS_NON_CORE
    reason: A genuine localization reflecting cortical myosin II during phagocytosis;
      peripheral to the core cytokinesis/migration functions.
    supported_by:
    - reference_id: PMID:12952073
      supporting_text: similar to that of myosin II at the rear end of locomoting
        cells and at the base
- term:
    id: GO:0045179
    label: apical cortex
  evidence_type: IDA
  original_reference_id: PMID:22902739
  qualifier: is_active_in
  review:
    summary: In tip epithelial cells that surround the stalk, myosin II localizes to
      the apical cortex to drive epithelial-tube constriction.
    action: KEEP_AS_NON_CORE
    reason: A specialized morphogenetic localization during multicellular
      development; genuine but non-core relative to the motor function.
    supported_by:
    - reference_id: PMID:22902739
      supporting_text: myosin II localizes apically in tip epithelial cells that
        surround the stalk
- term:
    id: GO:0030899
    label: calcium-dependent ATPase activity
  evidence_type: IDA
  original_reference_id: PMID:7806571
  qualifier: enables
  review:
    summary: Annotation to a calcium-dependent ATPase activity, cited to a study of
      the regulatory myosin light chain (RMLC/mlcR) gene disruption. The available
      abstract does not describe a Ca2+-dependent ATPase measurement for the heavy
      chain.
    action: UNDECIDED
    reason: Ca2+-ATPase is a non-physiological in vitro myosin assay, and the cited
      abstract (about RMLC disruption) does not document it. Unable to verify the
      basis of this specific molecular-function annotation from available text.
- term:
    id: GO:0048870
    label: cell motility
  evidence_type: IMP
  original_reference_id: PMID:15259052
  qualifier: involved_in
  review:
    summary: Myosin II shapes amoeboid locomotion, though keratocyte-like
      unidirectional movement can occur without it.
    action: KEEP_AS_NON_CORE
    reason: Myosin II is dispensable for some modes of unidirectional movement but
      maintains cell shape during motility; it modulates rather than powers
      locomotion.
    supported_by:
    - reference_id: PMID:15259052
      supporting_text: myosin II is dispensable for the unidirectional movement,
        though it likely
- term:
    id: GO:0048870
    label: cell motility
  evidence_type: IGI
  original_reference_id: PMID:15259052
  qualifier: involved_in
  review:
    summary: Genetic-interaction evidence (amiB/myosin double knockout) for a
      modulatory role of myosin II in amoeboid locomotion and shape maintenance.
    action: KEEP_AS_NON_CORE
    reason: Consistent with the IMP annotation from the same study; myosin II
      supports the characteristic migrating cell shape but is not strictly required
      for movement.
    supported_by:
    - reference_id: PMID:15259052
      supporting_text: functions in the maintenance of the characteristic half-moon
        shape
- term:
    id: GO:0060328
    label: cytoplasmic actin-based contraction involved in forward cell motility
  evidence_type: IMP
  original_reference_id: PMID:18388319
  qualifier: involved_in
  review:
    summary: Myosin II motor activity produces the actomyosin contractile forces
      that propel and retract the cell during forward migration.
    action: ACCEPT
    reason: Direct evidence that accumulated myosin II generates contractile
      retraction forces coordinated with actin-based propulsion; a central
      migratory role.
    supported_by:
    - reference_id: PMID:18388319
      supporting_text: the source of the retraction force is the motor activity of
        accumulated myosin
- term:
    id: GO:0032060
    label: bleb assembly
  evidence_type: IMP
  original_reference_id: PMID:26317626
  qualifier: acts_upstream_of_or_within
  review:
    summary: Blebbing (a myosin II-dependent, cortical-contraction-driven protrusion
      mode) is regulated by microtubule/inositol-lipid signaling.
    action: KEEP_AS_NON_CORE
    reason: Bleb formation requires myosin II-driven cortical contraction; this
      study addresses upstream regulation of blebbing. Genuine but non-core role.
    supported_by:
    - reference_id: PMID:16624291
      supporting_text: cortical contraction involving myosin-II
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:30559246
  qualifier: enables
  review:
    summary: Protein binding reflecting myosin II's incorporation into
      mechanoresponsive contractility kits.
    action: KEEP_AS_NON_CORE
    reason: A real assembly interaction, but the bare protein binding term is
      uninformative; retained as non-core with the contractility-kit context noted.
    supported_by:
    - reference_id: PMID:30559246
      supporting_text: Cellular contractility is governed by a control system of
        proteins that
- term:
    id: GO:0000146
    label: microfilament motor activity
  evidence_type: IDA
  original_reference_id: PMID:16982629
  qualifier: enables
  review:
    summary: Functional dissection of the myosin-2 N-terminal region shows its
      motor/motile activity and actin/ADP affinities, confirming actin-based motor
      function.
    action: ACCEPT
    reason: Truncations altering motile activity and actin affinity directly
      demonstrate the actin-based motor activity of Dictyostelium myosin-2. Core
      function.
    supported_by:
    - reference_id: PMID:16982629
      supporting_text: changes of similar extent in the affinity for ADP and
- term:
    id: GO:0000146
    label: microfilament motor activity
  evidence_type: IDA
  original_reference_id: PMID:19955408
  qualifier: enables
  review:
    summary: Charge manipulation of surface loops in Dictyostelium myosin II (class
      II) alters its sliding velocity, an assay of actin-based motor activity.
    action: ACCEPT
    reason: The study directly manipulates and measures the motility of Dictyostelium
      myosin II, supporting its microfilament motor activity.
    supported_by:
    - reference_id: PMID:19955408
      supporting_text: charge contents in loops 2 and 3 of Dictyostelium
- term:
    id: GO:0003774
    label: cytoskeletal motor activity
  evidence_type: IDA
  original_reference_id: PMID:15910751
  qualifier: enables
  review:
    summary: Actomyosin sliding assays using the Dictyostelium myosin II motor
      domain demonstrate cytoskeletal (actin-based) motor activity.
    action: ACCEPT
    reason: MgATPase and in vitro sliding measurements with the Dictyostelium myosin
      II motor domain confirm cytoskeletal motor activity.
    supported_by:
    - reference_id: PMID:15910751
      supporting_text: the motor domain of Dictyostelium myosin II
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:11106661
  qualifier: enables
  review:
    summary: Protein binding reflecting the direct interaction of myosin heavy chain
      kinase WD-repeat domains with myosin II filaments (myosin as the substrate).
    action: KEEP_AS_NON_CORE
    reason: A specific, informative interaction (MHCK targeting to myosin filaments),
      but the bare protein binding term understates it; retained as non-core with
      the partner noted.
    supported_by:
    - reference_id: PMID:11106661
      supporting_text: the mechanism of targeting involves direct binding of the WD
        repeat domains to the
- term:
    id: GO:0005515
    label: protein binding
  evidence_type: IPI
  original_reference_id: PMID:18504297
  qualifier: enables
  review:
    summary: Protein binding within the RasB/RasGEF Q/MHCK A signaling module that
      regulates myosin II assembly.
    action: KEEP_AS_NON_CORE
    reason: Reflects a regulatory interaction affecting myosin II function; the
      generic term is uninformative and the interaction is upstream regulatory
      rather than a core myosin activity.
    supported_by:
    - reference_id: PMID:18504297
      supporting_text: increased levels of unphosphorylated myosin II, resulting in
        myosin II
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IDA
  original_reference_id: PMID:16982629
  qualifier: enables
  review:
    summary: Nucleotide (ADP/ATP) affinity measurements on Dictyostelium myosin-2
      constructs confirm nucleotide binding by the motor domain.
    action: ACCEPT
    reason: The motor domain binds and hydrolyzes ATP; nucleotide-affinity changes
      were directly measured. Core function.
    supported_by:
    - reference_id: PMID:16982629
      supporting_text: changes of similar extent in the affinity for ADP and
- term:
    id: GO:0005524
    label: ATP binding
  evidence_type: IDA
  original_reference_id: PMID:4278009
  qualifier: enables
  review:
    summary: Biochemical characterization of isolated Dictyostelium myosin,
      including its ATPase activity.
    action: ACCEPT
    reason: The isolated myosin binds and hydrolyzes ATP; ATP binding is a core
      property of the motor domain.
    supported_by:
    - reference_id: PMID:4278009
      supporting_text: Isolation and characterization of myosin from amoebae of
        Dictyostelium
- term:
    id: GO:0005826
    label: actomyosin contractile ring
  evidence_type: IDA
  original_reference_id: PMID:9238018
  qualifier: is_active_in
  review:
    summary: Myosin II assembles into the functional contractile ring during
      cytokinesis (shown by its failure to do so in clathrin-minus cells).
    action: ACCEPT
    reason: Assembly of myosin II into the contractile ring is central to
      cytokinesis; a core localization/activity.
    supported_by:
    - reference_id: PMID:9238018
      supporting_text: failed to assemble myosin II into a functional contractile
        ring
- term:
    id: GO:0005856
    label: cytoskeleton
  evidence_type: IDA
  original_reference_id: PMID:2578450
  qualifier: is_active_in
  review:
    summary: A large fraction of cellular myosin II is associated with the
      Triton-insoluble cytoskeleton/cortical actin matrix.
    action: ACCEPT
    reason: Quantitative immunochemistry shows myosin II partitions with the
      cytoskeleton; correct though general relative to cell cortex.
    supported_by:
    - reference_id: PMID:2578450
      supporting_text: contain nearly half of the cell's myosin
- term:
    id: GO:0005938
    label: cell cortex
  evidence_type: IDA
  original_reference_id: PMID:16461463
  qualifier: is_active_in
  review:
    summary: Myosin II is highly enriched in and mechanically active at the cell
      cortex.
    action: ACCEPT
    reason: Cortical enrichment and mechanochemical activity of myosin II is a core
      localization underpinning cortical tension. Core.
    supported_by:
    - reference_id: PMID:16461463
      supporting_text: Highly enriched in the cell cortex, actin, myosin II
- term:
    id: GO:0030554
    label: adenyl nucleotide binding
  evidence_type: IDA
  original_reference_id: PMID:14620745
  qualifier: enables
  review:
    summary: Nucleotide-dissociation kinetics measured on the Dictyostelium
      cytoplasmic myosin II motor domain confirm adenine-nucleotide binding.
    action: ACCEPT
    reason: The motor domain binds adenine nucleotides (ATP/ADP); a general parent
      of ATP binding and correct.
    supported_by:
    - reference_id: PMID:14620745
      supporting_text: Dictyostelium cytoplasmic myosin II
- term:
    id: GO:0030864
    label: cortical actin cytoskeleton
  evidence_type: IDA
  original_reference_id: PMID:3243031
  qualifier: is_active_in
  review:
    summary: Immuno-EM localizes myosin II to the cortical actin matrix in lateral
      filament arrays.
    action: ACCEPT
    reason: Myosin II operates within the cortical actin cytoskeleton; a core
      localization for its contractile function.
    supported_by:
    - reference_id: PMID:3243031
      supporting_text: myosin II and ABP-120 in the cortical actin
- term:
    id: GO:0032982
    label: myosin filament
  evidence_type: IDA
  original_reference_id: PMID:4278009
  qualifier: is_active_in
  review:
    summary: Isolated Dictyostelium myosin forms filaments, the active
      force-generating assembly.
    action: ACCEPT
    reason: The heavy chain self-assembles into (thick) myosin filaments; core
      structural localization.
    supported_by:
    - reference_id: PMID:4278009
      supporting_text: Isolation and characterization of myosin from amoebae of
        Dictyostelium
- term:
    id: GO:0042641
    label: actomyosin
  evidence_type: IDA
  original_reference_id: PMID:4278009
  qualifier: is_active_in
  review:
    summary: The classic study characterized actomyosin-like proteins from
      Dictyostelium, of which myosin II is a component.
    action: ACCEPT
    reason: Myosin II is a defining component of actomyosin; correct localization.
    supported_by:
    - reference_id: PMID:4278009
      supporting_text: Isolation and characterization of myosin from amoebae of
        Dictyostelium
- term:
    id: GO:0042802
    label: identical protein binding
  evidence_type: IPI
  original_reference_id: PMID:2745547
  qualifier: enables
  review:
    summary: Rotary-shadowing shows myosin molecules self-associate into parallel
      dimers and tetramers via tail-tail interactions during filament assembly.
    action: ACCEPT
    reason: Homotypic self-assembly of myosin heavy chains through their tails is a
      core activity that builds bipolar thick filaments; captured by identical
      protein binding.
    supported_by:
    - reference_id: PMID:2745547
      supporting_text: Parallel dimers form tetramers by way of antiparallel
        interactions in their tail
- term:
    id: GO:0051015
    label: actin filament binding
  evidence_type: IDA
  original_reference_id: PMID:16982629
  qualifier: enables
  review:
    summary: Direct measurement of filamentous-actin affinity for Dictyostelium
      myosin-2 constructs.
    action: ACCEPT
    reason: The myosin II motor domain binds F-actin; actin affinity was directly
      measured. Core function.
    supported_by:
    - reference_id: PMID:16982629
      supporting_text: changes of similar extent in the affinity for ADP and
- term:
    id: GO:0051015
    label: actin filament binding
  evidence_type: IDA
  original_reference_id: PMID:18067324
  qualifier: enables
  review:
    summary: Kinetic analysis identifies myosin loop 4 as an actin-binding region
      that stabilizes the actomyosin complex.
    action: ACCEPT
    reason: Direct evidence that the Dictyostelium myosin II motor domain binds
      actin filaments. Core function.
    supported_by:
    - reference_id: PMID:18067324
      supporting_text: loop 4 is a functional actin-binding region that stabilizes
        actomyosin
- term:
    id: GO:0071889
    label: 14-3-3 protein binding
  evidence_type: IPI
  original_reference_id: PMID:20951045
  qualifier: enables
  review:
    summary: 14-3-3 associates directly with myosin II heavy chain to promote
      bipolar thick filament remodeling.
    action: KEEP_AS_NON_CORE
    reason: A specific, verified interaction that regulates myosin II filament
      dynamics during cytokinesis; a genuine binding activity but regulatory/non-core
      relative to the motor function.
    supported_by:
    - reference_id: PMID:20951045
      supporting_text: 14-3-3 interacts directly with myosin II heavy chain to
        promote bipolar thick
- term:
    id: GO:1903013
    label: response to differentiation-inducing factor 1
  evidence_type: HDA
  original_reference_id: PMID:25518940
  qualifier: acts_upstream_of_or_within
  review:
    summary: Phosphoproteomics after DIF-1 treatment detected changes in
      actomyosin-cytoskeletal signaling components, including myosin.
    action: KEEP_AS_NON_CORE
    reason: Reflects DIF-1-induced phosphorylation changes in cytoskeletal
      signaling; a developmental-signaling response rather than a core molecular
      function.
    supported_by:
    - reference_id: PMID:25518940
      supporting_text: components of the actinomyosin cytoskeletal signaling networks
- term:
    id: GO:1990753
    label: equatorial cell cortex
  evidence_type: IDA
  original_reference_id: PMID:19515202
  qualifier: is_active_in
  review:
    summary: Myosin II localizes to the equatorial cortex/furrow region of dividing
      cells.
    action: ACCEPT
    reason: Equatorial cortex enrichment underlies contractile-ring formation during
      cytokinesis; core localization.
    supported_by:
    - reference_id: PMID:19515202
      supporting_text: region of dividing cells
- term:
    id: GO:0051591
    label: response to cAMP
  evidence_type: IDA
  original_reference_id: PMID:2543508
  qualifier: involved_in
  review:
    summary: Cytoskeletal myosin content changes following chemotactic cAMP
      stimulation of Dictyostelium amoebae.
    action: KEEP_AS_NON_CORE
    reason: Myosin II redistributes in response to cAMP signaling during chemotaxis;
      a signaling-linked behavior rather than a core molecular function.
    supported_by:
    - reference_id: PMID:2543508
      supporting_text: Changes in the content of total cytoskeletal protein and
        cytoskeletal myosin were
- term:
    id: GO:0042542
    label: response to hydrogen peroxide
  evidence_type: IDA
  original_reference_id: PMID:21988699
  qualifier: involved_in
  review:
    summary: Site-directed and peroxide-induced methionine oxidation of Dictyostelium
      myosin II decreases actin-activated ATPase activity.
    action: KEEP_AS_NON_CORE
    reason: Documents oxidative sensitivity of myosin II function rather than a
      physiological signaling role; retained as non-core.
    supported_by:
    - reference_id: PMID:21988699
      supporting_text: peroxide treatment decreased actin-activated myosin ATPase
        activity
- term:
    id: GO:0006971
    label: hypotonic response
  evidence_type: IMP
  original_reference_id: PMID:19843280
  qualifier: acts_upstream_of_or_within
  review:
    summary: The cortical myosin II cytoskeleton contributes to contractile-vacuole
      function required for osmotic homeostasis.
    action: KEEP_AS_NON_CORE
    reason: Myosin II supports the periodic contractions of the contractile vacuole
      that protect against osmotic (hypotonic) stress; a downstream physiological
      role.
    supported_by:
    - reference_id: PMID:19843280
      supporting_text: myosin II null cells also results in enlarged CVs with
        impaired dynamics
- term:
    id: GO:0033275
    label: actin-myosin filament sliding
  evidence_type: IDA
  original_reference_id: PMID:19955408
  qualifier: involved_in
  review:
    summary: In vitro motility of Dictyostelium myosin II, measured as actin-myosin
      sliding velocity, is altered by surface-loop charge changes.
    action: ACCEPT
    reason: Direct measurement of actin-myosin filament sliding by Dictyostelium
      myosin II; a core mechanochemical activity.
    supported_by:
    - reference_id: PMID:19955408
      supporting_text: charge contents in loops 2 and 3 of Dictyostelium
- term:
    id: GO:0032060
    label: bleb assembly
  evidence_type: IMP
  original_reference_id: PMID:16926192
  qualifier: acts_upstream_of_or_within
  review:
    summary: Bleb formation at the leading edge during amoeboid movement requires
      myosin II activity.
    action: KEEP_AS_NON_CORE
    reason: Myosin II-driven cortical contraction is required for blebbing, a
      distinct protrusion mode contributing to motility; genuine but non-core.
    supported_by:
    - reference_id: PMID:16926192
      supporting_text: Their formation requires the activity of myosin II
- term:
    id: GO:0031034
    label: myosin filament assembly
  evidence_type: IDA
  original_reference_id: PMID:4278009
  qualifier: involved_in
  review:
    summary: Isolated Dictyostelium myosin self-assembles into filaments, a
      biochemically characterized process.
    action: ACCEPT
    reason: Myosin heavy chains self-assemble into bipolar thick filaments; myosin
      filament assembly is a core structural activity.
    supported_by:
    - reference_id: PMID:15492777
      supporting_text: forms bipolar thick filament (BTF) structures
- term:
    id: GO:0033275
    label: actin-myosin filament sliding
  evidence_type: IDA
  original_reference_id: PMID:16901894
  qualifier: involved_in
  review:
    summary: A point mutation in the SH1 helix of Dictyostelium myosin II impairs
      motile activity, assayed as actin-myosin sliding.
    action: ACCEPT
    reason: The single-molecule and in vitro motility measurements directly assay
      actin-myosin sliding by Dictyostelium myosin II. Core mechanochemical
      activity.
    supported_by:
    - reference_id: PMID:16901894
      supporting_text: significant impairment in motile activities
- term:
    id: GO:0030866
    label: cortical actin cytoskeleton organization
  evidence_type: IDA
  original_reference_id: PMID:16461463
  qualifier: involved_in
  review:
    summary: Myosin II mechanochemistry, antagonized by dynacortin crosslinking,
      shapes the dynamic behavior of the cortical actin cytoskeleton.
    action: KEEP_AS_NON_CORE
    reason: Myosin II contributes to cortical cytoskeleton dynamics via its
      contractile activity; a downstream organizational role rather than the core
      motor function.
    supported_by:
    - reference_id: PMID:16461463
      supporting_text: myosin II and dynacortin antagonistically regulate other
        active processes in the
- term:
    id: GO:0008104
    label: intracellular protein localization
  evidence_type: IMP
  original_reference_id: PMID:16339076
  qualifier: acts_upstream_of_or_within
  review:
    summary: Myosin II modulates the cleavage-furrow localization of the chromosomal
      passenger protein DdINCENP.
    action: KEEP_AS_NON_CORE
    reason: Myosin II influences localization of other furrow proteins as part of
      its cytokinesis role; a downstream effect rather than a core molecular
      function.
    supported_by:
    - reference_id: PMID:16339076
      supporting_text: the localization of DdINCENP at the cleavage furrow is
- term:
    id: GO:0032060
    label: bleb assembly
  evidence_type: IMP
  original_reference_id: PMID:16624291
  qualifier: acts_upstream_of_or_within
  review:
    summary: Chemoattractant-induced blebbing is driven by hydrostatic pressure from
      myosin II cortical contraction; myosin-null cells fail to bleb.
    action: KEEP_AS_NON_CORE
    reason: Myosin II is strictly required for bleb formation (cells lacking myosin
      II completely fail to bleb), but blebbing is a specialized motility behavior
      secondary to the core motor function.
    supported_by:
    - reference_id: PMID:16624291
      supporting_text: completely fail to bleb
references:
- id: GO_REF:0000002
  title: Gene Ontology annotation through association of InterPro records with GO
    terms
  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:0000117
  title: Electronic Gene Ontology annotations created by ARBA machine learning models
  findings: []
- id: PMID:10588668
  title: LvsA, a protein related to the mouse beige protein, is required for cytokinesis
    in Dictyostelium.
  findings:
  - statement: Myosin II localizes to the cleavage furrow at the start of cytokinesis.
    supporting_text: they initiate furrow formation with concomitant myosin II
      localization at the
  reference_review:
    relevance: MEDIUM
    correctness: VERIFIED
    review_notes: Supports myosin II furrow localization during cytokinesis (studied
      via the LvsA cytokinesis mutant).
- id: PMID:11106661
  title: WD repeat domains target dictyostelium myosin heavy chain kinases by binding
    directly to myosin filaments.
  findings:
  - statement: MHCK WD-repeat domains bind directly to myosin II filaments to target
      the kinase to its substrate.
    supporting_text: the mechanism of targeting involves direct binding of the WD
      repeat domains to the
- id: PMID:12952073
  title: Differential localization of the Dictyostelium kinase DPAKa during cytokinesis
    and cell migration.
  findings: []
- id: PMID:14620745
  title: Probing nucleotide dissociation from myosin in vitro using microgram quantities
    of myosin.
  findings: []
- id: PMID:15259052
  title: Keratocyte-like locomotion in amiB-null Dictyostelium cells.
  findings:
  - statement: Myosin II is dispensable for unidirectional keratocyte-like movement
      but maintains cell shape.
    supporting_text: myosin II is dispensable for the unidirectional movement, though
      it likely
- id: PMID:15492777
  title: 'Dictyostelium myosin bipolar thick filament formation: importance of charge
    and specific domains of the myosin rod.'
  findings:
  - statement: The myosin-II tail self-assembles into bipolar thick filaments in a
      regulated manner.
    supporting_text: forms bipolar thick filament (BTF) structures
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Directly supports myosin II self-assembly into bipolar thick
      filaments and its regulation.
- id: PMID:15855234
  title: Computer-assisted analysis of filopod formation and the role of myosin II
    heavy chain phosphorylation in Dictyostelium.
  findings:
  - statement: Myosin II heavy chain phosphorylation state regulates filopod
      formation.
    supporting_text: MHC phosphorylation-dephosphorylation plays a role in the
      regulation of filopod
- id: PMID:15894626
  title: Subsecond reorganization of the actin network in cell motility and chemotaxis.
  findings: []
  reference_review:
    relevance: LOW
    correctness: UNVERIFIED
    review_notes: Abstract concerns actin-network dynamics and does not establish a
      myosin II role; basis of the two IMP annotations to mhcA could not be verified.
- id: PMID:15910751
  title: Evidence against essential roles for subdomain 1 of actin in actomyosin sliding
    movements.
  findings: []
- id: PMID:16339076
  title: Contractile ring-independent localization of DdINCENP, a protein important
    for spindle stability and cytokinesis.
  findings: []
- id: PMID:16461463
  title: Dictyostelium myosin II mechanochemistry promotes active behavior of the
    cortex on long time scales.
  findings:
  - statement: Myosin II is highly enriched in the cell cortex and regulates cortical
      dynamics.
    supporting_text: Highly enriched in the cell cortex, actin, myosin II
- id: PMID:16624291
  title: Blebbing of Dictyostelium cells in response to chemoattractant.
  findings:
  - statement: Cells lacking myosin II completely fail to bleb; bleb expansion is
      driven by cortical contraction involving myosin II.
    supporting_text: cortical contraction involving myosin-II
- id: PMID:16901894
  title: A point mutation in the SH1 helix alters elasticity and thermal stability
    of myosin II.
  findings: []
- id: PMID:16926192
  title: Dissection of amoeboid movement into two mechanically distinct modes.
  findings:
  - statement: Bleb formation during amoeboid motility requires myosin II activity.
    supporting_text: Their formation requires the activity of myosin II
- id: PMID:16982629
  title: Functional characterization of the N-terminal region of myosin-2.
  findings:
  - statement: Truncations of Dictyostelium myosin-2 alter motile activity and
      actin/ADP affinity, and the SH3-like subdomain modulates motor activity.
    supporting_text: changes of similar extent in the affinity for ADP and
- id: PMID:17126332
  title: Time-resolved responses to chemoattractant, characteristic of the front and
    tail of Dictyostelium cells.
  findings:
  - statement: The cell tail/rear is specified by recruitment of filamentous myosin
      II.
    supporting_text: the tail by the recruitment of filamentous myosin-II
- id: PMID:18067324
  title: Kinetic characterization of the function of myosin loop 4 in the actin-myosin
    interaction.
  findings:
  - statement: Myosin loop 4 is an actin-binding region that stabilizes the
      actomyosin complex.
    supporting_text: loop 4 is a functional actin-binding region that stabilizes
      actomyosin
- id: PMID:18388319
  title: Actin-based propulsive forces and myosin-II-based contractile forces in migrating
    Dictyostelium cells.
  findings:
  - statement: Accumulated filamentous myosin II motor activity generates the
      retraction force in pseudopodia and the cell rear.
    supporting_text: the source of the retraction force is the motor activity of
      accumulated myosin
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Direct force-microscopy evidence for myosin II motor activity
      driving rear/pseudopod retraction during migration.
- id: PMID:18504297
  title: 'Linking Ras to myosin function: RasGEF Q, a Dictyostelium exchange factor
    for RasB, affects myosin II functions.'
  findings: []
- id: PMID:18725645
  title: Actin-binding cleft closure in myosin II probed by site-directed spin labeling
    and pulsed EPR.
  findings: []
- id: PMID:18854143
  title: An Elmo-like protein associated with myosin II restricts spurious F-actin
    events to coordinate phagocytosis and chemotaxis.
  findings:
  - statement: ElmoA physically associates with cortical actin and myosin II.
    supporting_text: ElmoA associates with cortical actin and myosin II
- id: PMID:18971336
  title: Visualizing myosin-actin interaction with a genetically-encoded fluorescent
    strain sensor.
  findings: []
- id: PMID:18980612
  title: Proteome analysis of Legionella vacuoles purified by magnetic immunoseparation
    reveals secretory and endosomal GTPases.
  findings: []
- id: PMID:19065153
  title: Cell adhesion molecules regulate contractile ring-independent cytokinesis
    in Dictyostelium discoideum.
  findings:
  - statement: Double knockouts of mhcA (myosin II) with paxB or vinA have more
      severe cytokinesis defects, confirming myosin II's role in furrow-based
      division.
    supporting_text: Double knockout strains lacking mhcA, which codes for myosin II
- id: PMID:19515202
  title: PTEN is a mechanosensing signal transducer for myosin II localization in
    Dictyostelium cells.
  findings:
  - statement: Myosin II co-localizes with PTEN at the posterior of migrating cells
      and the furrow of dividing cells.
    supporting_text: region of dividing cells
- id: PMID:19843280
  title: Roles of an unconventional protein kinase and myosin II in amoeba osmotic
    shock responses.
  findings:
  - statement: Myosin II is required for normal contractile-vacuole dynamics during
      osmotic responses.
    supporting_text: myosin II null cells also results in enlarged CVs with impaired
      dynamics
- id: PMID:19955408
  title: Unique charge distribution in surface loops confers high velocity on the
    fast motor protein Chara myosin.
  findings:
  - statement: Charge manipulation of loops 2 and 3 of Dictyostelium myosin II alters
      its sliding velocity.
    supporting_text: charge contents in loops 2 and 3 of Dictyostelium
- id: PMID:20200225
  title: A myosin IK-Abp1-PakB circuit acts as a switch to regulate phagocytosis efficiency.
  findings:
  - statement: Myosin II is present in the concentric protein rings of the phagocytic
      furrow.
    supporting_text: concentric overlapping rings of MyoK, Abp1, Arp3, coronin, and
      myosin II
- id: PMID:20351242
  title: Myosin complexed with ADP and blebbistatin reversibly adopts a conformation
    resembling the start point of the working stroke.
  findings: []
- id: PMID:20951045
  title: 14-3-3 coordinates microtubules, Rac, and myosin II to control cell mechanics
    and cytokinesis.
  findings:
  - statement: 14-3-3 interacts directly with myosin II heavy chain to promote
      bipolar thick filament remodeling.
    supporting_text: 14-3-3 interacts directly with myosin II heavy chain to promote
      bipolar thick
- id: PMID:21988699
  title: Structural and functional impact of site-directed methionine oxidation in
    myosin.
  findings:
  - statement: Peroxide oxidation of Dictyostelium myosin II decreases its
      actin-activated ATPase activity.
    supporting_text: peroxide treatment decreased actin-activated myosin ATPase
      activity
- id: PMID:22114350
  title: Actin cross-linking proteins cortexillin I and II are required for cAMP signaling
    during Dictyostelium chemotaxis and development.
  findings: []
- id: PMID:22379107
  title: A mechanosensory system governs myosin II accumulation in dividing cells.
  findings:
  - statement: Myosin II and cortexillin I form the core cortical mechanosensor that
      responds to mechanical stress.
    supporting_text: the mechanoenzyme myosin II and the actin cross-linker
      cortexillin I form a
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Establishes myosin II as a component of the cortical mechanosensor.
- id: PMID:22902739
  title: α-catenin and IQGAP regulate myosin localization to control epithelial tube
    morphogenesis in Dictyostelium.
  findings:
  - statement: Myosin II localizes apically in tip epithelial cells to drive
      epithelial-tube constriction.
    supporting_text: myosin II localizes apically in tip epithelial cells that
      surround the stalk
- id: PMID:23132928
  title: Delineating the core regulatory elements crucial for directed cell migration
    by examining folic-acid-mediated responses.
  findings: []
- id: PMID:23442953
  title: Myosin-II-mediated directional migration of Dictyostelium cells in response
    to cyclic stretching of substratum.
  findings:
  - statement: Cells accumulate myosin II where mechanical strain is received during
      cyclic substrate stretching.
    supporting_text: Dictyostelium cells accumulate myosin II at the portion of the
      cell where a
- id: PMID:2530629
  title: Expression and characterization of a functional myosin head fragment in Dictyostelium
    discoideum.
  findings:
  - statement: The recombinant Dictyostelium myosin head fragment has actin-activated
      ATPase activity and supports actin filament sliding.
    supporting_text: displayed actin-activated adenosine triphosphatase activity
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Direct evidence of the actin-based motor activity of the myosin II
      head.
- id: PMID:2543508
  title: Changes in the association of actin-binding proteins with the actin cytoskeleton
    during chemotactic stimulation of Dictyostelium discoideum.
  findings:
  - statement: Cytoskeletal myosin content changes following cAMP chemotactic
      stimulation.
    supporting_text: Changes in the content of total cytoskeletal protein and
      cytoskeletal myosin were
- id: PMID:25518940
  title: The Dictyostelium prestalk inducer differentiation-inducing factor-1 (DIF-1)
    triggers unexpectedly complex global phosphorylation changes.
  findings:
  - statement: DIF-1 induces phosphorylation changes in actomyosin cytoskeletal
      signaling components.
    supporting_text: components of the actinomyosin cytoskeletal signaling networks
- id: PMID:2578450
  title: Quantitative immunochemical studies of myosin in Dictyostelium discoideum.
  findings:
  - statement: Nearly half of cellular myosin partitions with the Triton-insoluble
      cytoskeleton and is released by ATP.
    supporting_text: If ATP is present, 98% of that myosin is released
- id: PMID:25887420
  title: Leaps and lulls in the developmental transcriptome of Dictyostelium discoideum.
  findings:
  - statement: mhcA is a cytoskeletal gene, differentially regulated during
      development and required for motility.
    supporting_text: the cytoskeletal genes abpA or mhcA, which are also required
      for motility
- id: PMID:26152465
  title: Proteomic profiling of the extracellular matrix (slime sheath) of Dictyostelium
    discoideum.
  findings: []
  reference_review:
    relevance: LOW
    correctness: VERIFIED
    review_notes: Slime-sheath proteomic detection of a cytoplasmic motor likely
      reflects contamination rather than genuine ECM localization.
- id: PMID:26317626
  title: Microtubule-Mediated Inositol Lipid Signaling Plays Critical Roles in Regulation
    of Blebbing.
  findings: []
- id: PMID:2721503
  title: 'Gene replacement in Dictyostelium: generation of myosin null mutants.'
  findings:
  - statement: Eliminating the conventional myosin gene abolishes normal cell
      division in suspension and impairs sporogenesis.
    supporting_text: the conventional myosin gene is required for growth in
      suspension, normal
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Genetic proof that mhcA is required for cytokinesis and later
      development.
- id: PMID:2745547
  title: 'Intermolecular versus intramolecular interactions of Dictyostelium myosin:
    possible regulation by heavy chain phosphorylation.'
  findings:
  - statement: Myosin molecules self-associate into parallel dimers and tetramers
      via tail-tail interactions during filament assembly.
    supporting_text: Parallel dimers form tetramers by way of antiparallel
      interactions in their tail
- id: PMID:30559246
  title: Contractility kits promote assembly of the mechanoresponsive cytoskeletal
    network.
  findings: []
- id: PMID:3243031
  title: Electron microscopic localization of myosin II and ABP-120 in the cortical
    actin matrix of Dictyostelium amoebae using IgG-gold conjugates.
  findings:
  - statement: Myosin II localizes to the cortical actin matrix and to unidentified
      cytoplasmic vesicles.
    supporting_text: with unidentified cytoplasmic vesicles
- id: PMID:3576222
  title: Disruption of the Dictyostelium myosin heavy chain gene by homologous recombination.
  findings:
  - statement: Myosin heavy chain disruption produces multinucleate cells defective
      in cytokinesis; hmm cells aggregate but are blocked later in development.
    supporting_text: genetic proof that the intact myosin molecule is required for
      cytokinesis
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Classic genetic proof of the myosin II cytokinesis requirement.
- id: PMID:36165849
  title: The lectin Discoidin I acts in the cytoplasm to help assemble the contractile
    machinery.
  findings:
  - statement: The contractility machinery (including myosin II) organizes into
      higher-order cytoplasmic contractility kits.
    supporting_text: the contractility machinery organizes into higher order
      assemblies termed
- id: PMID:37987147
  title: Adaptive pathfinding by nucleokinesis during amoeboid migration.
  findings: []
- id: PMID:40712579
  title: Inchworm migration facilitates amoeboid cell adaptation to high-adhesion
    environments.
  findings:
  - statement: Inchworm migration on adhesive surfaces repurposes the cytokinesis
      (actomyosin) machinery.
    supporting_text: the repurposing of cytokinesis machinery for migration mode
      shifting
- id: PMID:41332277
  title: The RNA-binding protein RNP1A is essential and interacts with contractility
    kit proteins to facilitate cell mechanics.
  findings:
  - statement: Myosin II, cortexillin I and IQGAP1 assemble in the cytoplasm into
      mechanoresponsive contractility kits.
    supporting_text: myosin II, cortexillin I and IQGAP1 assemble in the cytoplasm
      into
- id: PMID:41353402
  title: Talin force coupling underlies eukaryotic cell-substrate adhesion.
  findings: []
  reference_review:
    relevance: LOW
    correctness: UNVERIFIED
    review_notes: Focuses on talin-A/SibA force coupling; a direct myosin II
      interaction could not be verified from the available text.
- id: PMID:4278009
  title: Biochemical and structural studies of actomyosin-like proteins from non-muscle
    cells. Isolation and characterization of myosin from amoebae of Dictyostelium
    discoideum.
  findings:
  - statement: Foundational isolation and biochemical/structural characterization of
      Dictyostelium myosin (myosin II).
    supporting_text: Isolation and characterization of myosin from amoebae of
      Dictyostelium
- id: PMID:7806571
  title: Targeted disruption of the Dictyostelium RMLC gene produces cells defective
    in cytokinesis and development.
  findings: []
  reference_review:
    relevance: MEDIUM
    correctness: UNVERIFIED
    review_notes: Concerns the regulatory myosin light chain (mlcR); the cited
      calcium-dependent ATPase activity for the heavy chain could not be verified
      from the abstract.
- id: PMID:8552657
  title: Myosin dynamics in live Dictyostelium cells.
  findings:
  - statement: GFP-myosin concentrates in the cleavage furrow during cytokinesis and
      in the posterior cortex of migrating cells, and transiently in retracting
      pseudopod tips.
    supporting_text: GFP-myosin is concentrated in the cleavage furrow during
      cytokinesis and in the
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Live-cell evidence for the dynamic localization of myosin II to
      furrow, rear cortex and pseudopod tips.
- id: PMID:8874966
  title: Dictyostelium cell shape generation requires myosin II.
  findings:
  - statement: Myosin II is required to generate and maintain three-dimensional cell
      shape.
    supporting_text: 3D cell shape generation requires myosin II
  reference_review:
    relevance: HIGH
    correctness: VERIFIED
    review_notes: Establishes the cortical-tension/cell-shape role of myosin II.
- id: PMID:9238018
  title: A novel role for clathrin in cytokinesis.
  findings:
  - statement: Myosin II must assemble into a functional contractile ring for
      cytokinesis.
    supporting_text: failed to assemble myosin II into a functional contractile ring
core_functions:
- description: Force-generating, actin-activated ATPase motor. The globular head
    domain binds actin filaments and hydrolyzes ATP to slide antiparallel actin
    filaments, generating contractile force at the cell cortex. As the heavy chain
    of the two-headed myosin II hexamer, it powers cortical tension, cleavage-furrow
    contraction during cytokinesis, and rear/tail retraction during migration.
  molecular_function:
    id: GO:0000146
    label: microfilament motor activity
  directly_involved_in:
  - id: GO:0000281
    label: mitotic cytokinesis
  locations:
  - id: GO:0005938
    label: cell cortex
  - id: GO:0032154
    label: cleavage furrow
  in_complex:
    id: GO:0016460
    label: myosin II complex
  supported_by:
  - reference_id: PMID:2530629
    supporting_text: displayed actin-activated adenosine triphosphatase activity
  - reference_id: PMID:3576222
    supporting_text: genetic proof that the intact myosin molecule is required for
      cytokinesis
  - reference_id: PMID:18388319
    supporting_text: the source of the retraction force is the motor activity of
      accumulated myosin
- description: Self-assembly into bipolar thick filaments. Two heavy chains dimerize
    through their coiled-coil tails and self-associate tail-to-tail into bipolar
    thick filaments, the functional force-generating assembly; this assembly is
    reversibly regulated by heavy chain phosphorylation.
  molecular_function:
    id: GO:0042802
    label: identical protein binding
  directly_involved_in:
  - id: GO:0031034
    label: myosin filament assembly
  locations:
  - id: GO:0032982
    label: myosin filament
  supported_by:
  - reference_id: PMID:2745547
    supporting_text: Parallel dimers form tetramers by way of antiparallel
      interactions in their tail
  - reference_id: PMID:15492777
    supporting_text: forms bipolar thick filament (BTF) structures
- description: ATP-dependent actin filament binding. The motor domain binds
    filamentous actin in a nucleotide-dependent manner, an integral step of the
    mechanochemical cycle that couples ATP hydrolysis to actin-myosin filament
    sliding.
  molecular_function:
    id: GO:0051015
    label: actin filament binding
  directly_involved_in:
  - id: GO:0033275
    label: actin-myosin filament sliding
  supported_by:
  - reference_id: PMID:18067324
    supporting_text: loop 4 is a functional actin-binding region that stabilizes
      actomyosin
  - reference_id: PMID:16901894
    supporting_text: significant impairment in motile activities