ApiLoc - A database of published protein sub-cellular localisation in Apicomplexa

version 3 (curated until May 28, 2011)

A family of intermediate filament-like proteins is sequentially assembled into the cytoskeleton of Toxoplasma gondii.

Anderson-White, B. R., Ivey, F. D., Cheng, K., Szatanek, T., Lorestani, A., Beckers, C. J., Ferguson, D. J., Sahoo, N., Gubbels, M. J. (2011 Jan, Cell Microbiol)

The intracellular protozoan parasite Toxoplasma gondii divides by a unique process of internal budding that involves the assembly of two daughter cells within the mother. The cytoskeleton of Toxoplasma, which is composed of microtubules associated with an inner membrane complex (IMC), has an important role in this process. The IMC, which is directly under the plasma membrane, contains a set of flattened membranous sacs lined on the cytoplasmic side by a network of filamentous proteins. This network contains a family of intermediate filament-like proteins or IMC proteins. In order to elucidate the division process, we have characterized a 14-member subfamily of Toxoplasma IMC proteins that share a repeat motif found in proteins associated with the cortical alveoli in all alveolates. By creating fluorescent protein fusion reporters for the family members we determined the spatiotemporal patterns of all 14 IMC proteins through tachyzoite development. This revealed several distinct distribution patterns and some provide the basis for novel structural models such as the assembly of certain family members into the basal complex. Furthermore we identified IMC15 as an early marker of budding and, lastly, the dynamic patterns observed throughout cytokinesis provide a timeline for daughter parasite development and division.

PubMed: 20698859, full text

Localisation information

TGME49_031640 (IMC1, ALV1, IMC, NET1) membrane skeletal protein IMC1

Experimental localisation: mother cytoskeleton during tachyzoite budding, daughter cytoskeleton during tachyzoite budding
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "When IMC1 and IMC3 are compared it is clear that more IMC3 is associated with the budding daughter cytoskeletons than with the cytoskeleton of the mother cell as opposed to the more equal distribution that IMC1 exhibits (Fig. 2A, B, E and F)."
  • Microscopy type: light
  • Microscopy method: Monoclonal antibody, YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: mother cytoskeleton and daughter cytoskeleton during tachyzoite budding

TGME49_016000 (IMC3) inner membrane complex protein IMC3

Experimental localisation: daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "When IMC1 and IMC3 are compared it is clear that more IMC3 is associated with the budding daughter cytoskeletons than with the cytoskeleton of the mother cell as opposed to the more equal distribution that IMC1 exhibits (Fig.ᅠ2A, B, E and F). The high intensity of IMC3 is maintained in the recently emerged daughters but then drops to lower basal levels in fully mature daughters (Figsᅠ2A and S2)."
  • Microscopy type: light
  • Microscopy method: antibody, YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: budding daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite

TGME49_031630 (IMC4) membrane skeletal protein IMC1, putative

Experimental localisation: mother cytoskeleton during tachyzoite budding, daughter cytoskeleton during tachyzoite budding
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "When IMC4 is compared with IMC1 and IMC3 using a parasite line expressing YFP–IMC4 it is found to localize like IMC1 with equal distribution in the mother and daughter buds (Fig. S4A and B). "
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: mother cytoskeleton and daughter cytoskeleton during tachyzoite budding

TGME49_024530 (IMC5) inner membrane complex associated protein 4

Experimental localisation: basal complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Furthermore, we generated a specific antiserum against the N-terminus of IMC5, which confirmed its localization to the basal complex (Figs 5B and S3C)."
  • Microscopy type: light
  • Microscopy method: antibody to N terminus
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: basal complex during intracellular tachyzoite

TGME49_020270 (IMC6) hypothetical protein, conserved

Experimental localisation: daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Among the novel IMC proteins we identified two, IMC6 and IMC10, which show a localization pattern like IMC3 (Figsᅠ2C, D, G, H and S4CヨF)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: budding daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite

TGME49_022220 (IMC7) articulin 4

Experimental localisation: mature cortical inner membrane complex during before initiation of budding of tachyzoites
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In contrast to the IMC proteins described above, IMC7, 12 and 14 are only found in the mature cortical IMC."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag, C terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: mature cortical IMC during before initiation of budding of tachyzoites
  • Comment: native promoter

TGME49_024520 (IMC8) hypothetical protein

Experimental localisation: exclusively basal complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Surprisingly, we identified several IMC proteins that exclusively localize to the basal complex in mature parasites: IMC5, 8, 9 and 13 (Fig. 5)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: exclusively basal complex during intracellular tachyzoite

TGME49_026220 (IMC9) hypothetical protein

Experimental localisation: exclusively basal complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Surprisingly, we identified several IMC proteins that exclusively localize to the basal complex in mature parasites: IMC5, 8, 9 and 13 (Fig. 5)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: exclusively basal complex during intracellular tachyzoite

TGME49_030210 (IMC10) hypothetical protein

Experimental localisation: daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Among the novel IMC proteins we identified two, IMC6 and IMC10, which show a localization pattern like IMC3 (Figsᅠ2C, D, G, H and S4CヨF)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: budding daughter cytoskeleton during tachyzoite budding, lower basal levels of cytoskeleton during fully mature tachyzoite

TGME49_039770 (IMC11) hypothetical protein

Experimental localisation: apical cap of inner membrane complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Expression of a YFP-tagged IMC11 driven by either the ptub or its endogenous promoter resulted in very weak expression of YFP in an area of the cortex known as the apical cap as well as an even weaker localization to the basal end of the IMC (Fig. S9). "
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: apical cap of IMC during intracellular tachyzoite

TGME49_048700 (IMC12) hypothetical protein, conserved

Experimental localisation: mature cortical inner membrane complex during before initiation of budding of tachyzoites
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In contrast to the IMC proteins described above, IMC7, 12 and 14 are only found in the mature cortical IMC."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag, C terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: mature cortical IMC during before initiation of budding of tachyzoites
  • Comment: native promoter

TGME49_053470 (IMC13) hypothetical protein, conserved

Experimental localisation: exclusively basal complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Surprisingly, we identified several IMC proteins that exclusively localize to the basal complex in mature parasites: IMC5, 8, 9 and 13 (Fig. 5)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag, C terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1
  • Localisation record: exclusively basal complex during intracellular tachyzoite

TGME49_060540 (IMC14) hypothetical protein

Experimental localisation: mature cortical inner membrane complex during before initiation of budding of tachyzoites
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "In contrast to the IMC proteins described above, IMC7, 12 and 14 are only found in the mature cortical IMC."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag, C terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1, gene model inconsistent?
  • Localisation record: mature cortical IMC during before initiation of budding of tachyzoites
  • Comment: native promoter

TGME49_075670 (IMC15) hypothetical protein, conserved

Experimental localisation: mature cortical inner membrane complex during intracellular tachyzoite, daughter inner membrane complex during intracellular tachyzoite, apical cap during intracellular tachyzoite, basal complex during intracellular tachyzoite, novel localisation at apical cap during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "YFP–IMC15, when driven by ptub, localizes to the mature cortical IMC, the budding daughter IMC, the apical cap, and the basal complex in addition to novel localization at the very apical end and the centrosomes (Fig. 4)."
  • Microscopy type: light
  • Microscopy method: N terminal YFP tag
  • Strain: RH
  • Gene model mapping comments: Taken directly from publication, supplementary table S1, gene model inconsistent?
  • Localisation record: mature cortical IMC and daughter IMC and apical cap and basal complex and novel localisation at apical cap during intracellular tachyzoite

TGME49_023940 (GAP45) hypothetical protein

Experimental localisation: inner membrane complex during mitosis of intracellular tachyzoite, periphery of parasite during emerging daughter tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "To verify that expression of YFP–IMC7, 12 and 14 do not interfere with maturation we used a glideosome component, GAP45, which is incorporated into the IMC upon daughter maturation (Agop-Nersesian et al., 2009). As shown in Fig. 3F, GAP45 did associate with the cortex of the emerging daughters expressing cytoplasmically localized YFP–IMC7, while some IMC7 is still in the cortex of the disassembling mother."
  • Microscopy type: light
  • Microscopy method: antibody
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: IMC during daughter maturation, cortex during emerging daughter

TGME49_058410 (PhIL1) hypothetical protein

Experimental localisation: apical cap of inner membrane complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "The localization to the apical cap was confirmed through coexpression of a CherryRFP-tagged version of PhIL1, an IMC-associated protein of unknown function (Gilk et al., 2006) (Fig. S9C)."
  • Microscopy type: light
  • Microscopy method: cherryRFP tag
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: apical cap of IMC during intracellular tachyzoite

TGME49_110440 (MORN1) phosphatidylinositol-4-phosphate 5-kinase, putative

Experimental localisation: basal complex during intracellular tachyzoite
  • Species: Toxoplasma gondii
  • Quote inferring localisation: "Using a MORN1 antibody, which highlights the basal complex (Gubbels et al., 2006), the basal localization of YFP–IMC11 is supported (Fig. S9D), but the poor YFP signal again did not permit a firm colocalization assignment."
  • Microscopy type: light
  • Microscopy method: antibody directly to protein
  • Strain: RH
  • Gene model mapping comments: inferred from another publication
  • Localisation record: basal complex during intracellular tachyzoite