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Stepping stone: a cytohesin adaptor for membrane cytoskeleton restraint in the syncytial Drosophila embryo.

Liu J, Lee DM, Yu CG, Angers S, Harris TJ - Mol. Biol. Cell (2014)

Bottom Line: Elevating Sstn furrow levels had no effect on the steppke phenotype, but elevating Steppke furrow levels reversed the sstn phenotype, suggesting that Steppke acts downstream of Sstn and that additional mechanisms can recruit Steppke to furrows.Finally, the coiled-coil domain of Steppke was required for Sstn binding and in addition homodimerization, and its removal disrupted Steppke furrow localization and activity in vivo.Overall we propose that Sstn acts as a cytohesin adaptor that promotes Steppke activity for localized membrane cytoskeleton restraint in the syncytial Drosophila embryo.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.

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Sequences analyses place Sstn within a conserved group of insect proteins with similarity to human FRMD4A. (A) Predicted domain structures of Sstn (CG6945) and similar proteins in other insects and humans: CC; coiled-coil; CR conserved region. (B) Matrix of blastp results. Blast queries (the proteins shown in A) are listed in the first column. The following columns show the blast hits in the other species, with the rank of the match among other proteins in the species (all are the top-ranked match in other species: 1), the expected score for the match, and the identical residues over the total residues in the blast result. Matches centered on the CC domain and CR are shown in orange and blue, respectively. (C) Multiple alignments of the CC domain and CR for the proteins shown in A. Note the high sequence identity for the CR among all of the insect species (Dm, Dv, Md, Dp, and Ae). Note the high sequence identity for the CC domains of butterfly (Dp), ant (Ae), and human (Hs) and the high sequence identity for the CC domains of Drosophila species (Dm and Dv) and house fly (Md).
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Figure 1: Sequences analyses place Sstn within a conserved group of insect proteins with similarity to human FRMD4A. (A) Predicted domain structures of Sstn (CG6945) and similar proteins in other insects and humans: CC; coiled-coil; CR conserved region. (B) Matrix of blastp results. Blast queries (the proteins shown in A) are listed in the first column. The following columns show the blast hits in the other species, with the rank of the match among other proteins in the species (all are the top-ranked match in other species: 1), the expected score for the match, and the identical residues over the total residues in the blast result. Matches centered on the CC domain and CR are shown in orange and blue, respectively. (C) Multiple alignments of the CC domain and CR for the proteins shown in A. Note the high sequence identity for the CR among all of the insect species (Dm, Dv, Md, Dp, and Ae). Note the high sequence identity for the CC domains of butterfly (Dp), ant (Ae), and human (Hs) and the high sequence identity for the CC domains of Drosophila species (Dm and Dv) and house fly (Md).

Mentions: To assess the properties of the Sstn, we conducted sequence analyses. The protein contained a predicted CC domain in its N-terminal region but had no other predicted domains (Figure 1A). BLAST searches identified a C-terminal conserved region (CR) with high identity to sequences in a number of predicted insect proteins (Figure 1, A–C). Bioinformatic analyses of these proteins revealed that they also contain a predicted N-terminal CC domain (Figure 1A). Moreover, the proteins from monarch butterflies (Danaus plexippus) and leaf-cutter ants (Acromyrmex echinatior) were previously annotated as FRMD4A-like proteins, although they lack the FERM domain of FRMD4A. For these proteins, our BLAST analyses revealed that their top Drosophila hit was Sstn, whereas their top human hit was a predicted FRMD4A isoform (Figure 1B). Their similarity with Sstn occurs in the CR, as mentioned, but their similarity with human FRMD4A occurs within their CC domains (color coding in Figure 1B).


Stepping stone: a cytohesin adaptor for membrane cytoskeleton restraint in the syncytial Drosophila embryo.

Liu J, Lee DM, Yu CG, Angers S, Harris TJ - Mol. Biol. Cell (2014)

Sequences analyses place Sstn within a conserved group of insect proteins with similarity to human FRMD4A. (A) Predicted domain structures of Sstn (CG6945) and similar proteins in other insects and humans: CC; coiled-coil; CR conserved region. (B) Matrix of blastp results. Blast queries (the proteins shown in A) are listed in the first column. The following columns show the blast hits in the other species, with the rank of the match among other proteins in the species (all are the top-ranked match in other species: 1), the expected score for the match, and the identical residues over the total residues in the blast result. Matches centered on the CC domain and CR are shown in orange and blue, respectively. (C) Multiple alignments of the CC domain and CR for the proteins shown in A. Note the high sequence identity for the CR among all of the insect species (Dm, Dv, Md, Dp, and Ae). Note the high sequence identity for the CC domains of butterfly (Dp), ant (Ae), and human (Hs) and the high sequence identity for the CC domains of Drosophila species (Dm and Dv) and house fly (Md).
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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Figure 1: Sequences analyses place Sstn within a conserved group of insect proteins with similarity to human FRMD4A. (A) Predicted domain structures of Sstn (CG6945) and similar proteins in other insects and humans: CC; coiled-coil; CR conserved region. (B) Matrix of blastp results. Blast queries (the proteins shown in A) are listed in the first column. The following columns show the blast hits in the other species, with the rank of the match among other proteins in the species (all are the top-ranked match in other species: 1), the expected score for the match, and the identical residues over the total residues in the blast result. Matches centered on the CC domain and CR are shown in orange and blue, respectively. (C) Multiple alignments of the CC domain and CR for the proteins shown in A. Note the high sequence identity for the CR among all of the insect species (Dm, Dv, Md, Dp, and Ae). Note the high sequence identity for the CC domains of butterfly (Dp), ant (Ae), and human (Hs) and the high sequence identity for the CC domains of Drosophila species (Dm and Dv) and house fly (Md).
Mentions: To assess the properties of the Sstn, we conducted sequence analyses. The protein contained a predicted CC domain in its N-terminal region but had no other predicted domains (Figure 1A). BLAST searches identified a C-terminal conserved region (CR) with high identity to sequences in a number of predicted insect proteins (Figure 1, A–C). Bioinformatic analyses of these proteins revealed that they also contain a predicted N-terminal CC domain (Figure 1A). Moreover, the proteins from monarch butterflies (Danaus plexippus) and leaf-cutter ants (Acromyrmex echinatior) were previously annotated as FRMD4A-like proteins, although they lack the FERM domain of FRMD4A. For these proteins, our BLAST analyses revealed that their top Drosophila hit was Sstn, whereas their top human hit was a predicted FRMD4A isoform (Figure 1B). Their similarity with Sstn occurs in the CR, as mentioned, but their similarity with human FRMD4A occurs within their CC domains (color coding in Figure 1B).

Bottom Line: Elevating Sstn furrow levels had no effect on the steppke phenotype, but elevating Steppke furrow levels reversed the sstn phenotype, suggesting that Steppke acts downstream of Sstn and that additional mechanisms can recruit Steppke to furrows.Finally, the coiled-coil domain of Steppke was required for Sstn binding and in addition homodimerization, and its removal disrupted Steppke furrow localization and activity in vivo.Overall we propose that Sstn acts as a cytohesin adaptor that promotes Steppke activity for localized membrane cytoskeleton restraint in the syncytial Drosophila embryo.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada.

Show MeSH