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The Drosophila gene abnormal spindle encodes a novel microtubule-associated protein that associates with the polar regions of the mitotic spindle.

Saunders RD, Avides MC, Howard T, Gonzalez C, Glover DM - J. Cell Biol. (1997)

Bottom Line: Wild-type Asp protein copurifies with microtubules and is not released by salt concentrations known to dissociate most other microtubule-associated proteins.The central 579-amino acid segment of the molecule contains one short motif homologous to sequences in a number of actin bundling proteins and a second motif present at the calmodulin binding sites of several proteins.Immunofluorescence studies show that the wild-type Asp protein is localized to the polar regions of the spindle immediately surrounding the centrosome.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Campaign, Cell Cycle Genetics Group, Department of Anatomy and Physiology, University of Dundee, Dundee DD1 4HN, Scotland.

ABSTRACT
abnormal spindle, a gene required for normal spindle structure and function in Drosophila melanogaster, lies immediately adjacent the gene tolloid at 96A/B. It encodes a 220-kD polypeptide with a predicted pI of 10.8. The recessive mutant allele asp1 directs the synthesis of a COOH terminally truncated or internally deleted peptide of approximately 124 kD. Wild-type Asp protein copurifies with microtubules and is not released by salt concentrations known to dissociate most other microtubule-associated proteins. The bacterially expressed NH2-terminal 512-amino acid peptide, which has a number of potential phosphorylation sites for p34(cdc2) and MAP kinases, strongly binds to microtubules. The central 579-amino acid segment of the molecule contains one short motif homologous to sequences in a number of actin bundling proteins and a second motif present at the calmodulin binding sites of several proteins. Immunofluorescence studies show that the wild-type Asp protein is localized to the polar regions of the spindle immediately surrounding the centrosome. These findings are discussed in relation to the known spindle abnormalities in asp mutants.

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(A) The sequence of the Asp protein. Consensus sites  for phosphorylation by p34cdc2 and MAP kinases are shown. Also  shown are the putative actin and calmodulin binding sites. (B)  Comparison of actin binding motifs. Comparison between Asp  putative actin binding site and actin binding sites present in α-actinin, spectrin, plastin, ABP120, dystrophin, and fimbrin. Only a selection of these actin binding domains is shown. Identical residues to Asp are shaded. (C) Comparison of calmodulin binding  motifs. A comparison between the Asp putative calmodulin binding site and the calmodulin binding sites present in a number of  other proteins. This list is not comprehensive. Identical residues  have been shaded.
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Figure 3: (A) The sequence of the Asp protein. Consensus sites for phosphorylation by p34cdc2 and MAP kinases are shown. Also shown are the putative actin and calmodulin binding sites. (B) Comparison of actin binding motifs. Comparison between Asp putative actin binding site and actin binding sites present in α-actinin, spectrin, plastin, ABP120, dystrophin, and fimbrin. Only a selection of these actin binding domains is shown. Identical residues to Asp are shaded. (C) Comparison of calmodulin binding motifs. A comparison between the Asp putative calmodulin binding site and the calmodulin binding sites present in a number of other proteins. This list is not comprehensive. Identical residues have been shaded.

Mentions: The 6.5-kb asp cDNA encodes a predicted polypeptide of 1,863–amino acid residues that has no homologues in the GenBank/EMBL/DDBJ database (Fig. 3 A). The asp protein is predominantly hydrophilic and strikingly basic, having a calculated pI of 10.8. Its secondary structure is predicted to be mostly α-helical. Analysis of the protein using the COILS program shows that short stretches of amino acids near the COOH terminus have the potential to form a coiled coil. There is a small sequence lying between residues 848 and 870 that has significant similarity to the core actin binding domain of a number of actin binding proteins, such as α-actinin (Noegel et al., 1987; Blanchard et al., 1989), fimbrin, spectrin, dystrophin (de Arruda et al., 1990; Matsudaira, 1991), and the Dictyostelium discoideum ABP120 (Bresnick et al. 1990; Fig. 3 B). These proteins either bundle actin filaments together (for example α-actinin) or attach actin filaments to other cellular structures. A second sequence lying between residues 938 and 968 corresponds to the conserved calmodulin binding (IQ) motif (Cheney and Mooseker, 1992) present in neuromodulin, a neuron-specific membrane-associated protein (Chapman et al., 1991); neurogranin, a neuron specific protein kinase C substrate (Baudier et al., 1991); the igloo gene product, a calmodulin-binding protein from the Drosophila central nervous system (Neel and Young, 1994); and in the “neck” regions of most forms of conventional and nonconventional myosin (for review see Cheney and Mooseker, 1992; Fig. 3 C). In addition Asp shows six consensus sites for phosphorylation by p34cdc2 and four consensus sites for phosphorylation by MAP kinase. Interestingly, these are all clustered in the NH2-terminal third of the molecule.


The Drosophila gene abnormal spindle encodes a novel microtubule-associated protein that associates with the polar regions of the mitotic spindle.

Saunders RD, Avides MC, Howard T, Gonzalez C, Glover DM - J. Cell Biol. (1997)

(A) The sequence of the Asp protein. Consensus sites  for phosphorylation by p34cdc2 and MAP kinases are shown. Also  shown are the putative actin and calmodulin binding sites. (B)  Comparison of actin binding motifs. Comparison between Asp  putative actin binding site and actin binding sites present in α-actinin, spectrin, plastin, ABP120, dystrophin, and fimbrin. Only a selection of these actin binding domains is shown. Identical residues to Asp are shaded. (C) Comparison of calmodulin binding  motifs. A comparison between the Asp putative calmodulin binding site and the calmodulin binding sites present in a number of  other proteins. This list is not comprehensive. Identical residues  have been shaded.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2139842&req=5

Figure 3: (A) The sequence of the Asp protein. Consensus sites for phosphorylation by p34cdc2 and MAP kinases are shown. Also shown are the putative actin and calmodulin binding sites. (B) Comparison of actin binding motifs. Comparison between Asp putative actin binding site and actin binding sites present in α-actinin, spectrin, plastin, ABP120, dystrophin, and fimbrin. Only a selection of these actin binding domains is shown. Identical residues to Asp are shaded. (C) Comparison of calmodulin binding motifs. A comparison between the Asp putative calmodulin binding site and the calmodulin binding sites present in a number of other proteins. This list is not comprehensive. Identical residues have been shaded.
Mentions: The 6.5-kb asp cDNA encodes a predicted polypeptide of 1,863–amino acid residues that has no homologues in the GenBank/EMBL/DDBJ database (Fig. 3 A). The asp protein is predominantly hydrophilic and strikingly basic, having a calculated pI of 10.8. Its secondary structure is predicted to be mostly α-helical. Analysis of the protein using the COILS program shows that short stretches of amino acids near the COOH terminus have the potential to form a coiled coil. There is a small sequence lying between residues 848 and 870 that has significant similarity to the core actin binding domain of a number of actin binding proteins, such as α-actinin (Noegel et al., 1987; Blanchard et al., 1989), fimbrin, spectrin, dystrophin (de Arruda et al., 1990; Matsudaira, 1991), and the Dictyostelium discoideum ABP120 (Bresnick et al. 1990; Fig. 3 B). These proteins either bundle actin filaments together (for example α-actinin) or attach actin filaments to other cellular structures. A second sequence lying between residues 938 and 968 corresponds to the conserved calmodulin binding (IQ) motif (Cheney and Mooseker, 1992) present in neuromodulin, a neuron-specific membrane-associated protein (Chapman et al., 1991); neurogranin, a neuron specific protein kinase C substrate (Baudier et al., 1991); the igloo gene product, a calmodulin-binding protein from the Drosophila central nervous system (Neel and Young, 1994); and in the “neck” regions of most forms of conventional and nonconventional myosin (for review see Cheney and Mooseker, 1992; Fig. 3 C). In addition Asp shows six consensus sites for phosphorylation by p34cdc2 and four consensus sites for phosphorylation by MAP kinase. Interestingly, these are all clustered in the NH2-terminal third of the molecule.

Bottom Line: Wild-type Asp protein copurifies with microtubules and is not released by salt concentrations known to dissociate most other microtubule-associated proteins.The central 579-amino acid segment of the molecule contains one short motif homologous to sequences in a number of actin bundling proteins and a second motif present at the calmodulin binding sites of several proteins.Immunofluorescence studies show that the wild-type Asp protein is localized to the polar regions of the spindle immediately surrounding the centrosome.

View Article: PubMed Central - PubMed

Affiliation: Cancer Research Campaign, Cell Cycle Genetics Group, Department of Anatomy and Physiology, University of Dundee, Dundee DD1 4HN, Scotland.

ABSTRACT
abnormal spindle, a gene required for normal spindle structure and function in Drosophila melanogaster, lies immediately adjacent the gene tolloid at 96A/B. It encodes a 220-kD polypeptide with a predicted pI of 10.8. The recessive mutant allele asp1 directs the synthesis of a COOH terminally truncated or internally deleted peptide of approximately 124 kD. Wild-type Asp protein copurifies with microtubules and is not released by salt concentrations known to dissociate most other microtubule-associated proteins. The bacterially expressed NH2-terminal 512-amino acid peptide, which has a number of potential phosphorylation sites for p34(cdc2) and MAP kinases, strongly binds to microtubules. The central 579-amino acid segment of the molecule contains one short motif homologous to sequences in a number of actin bundling proteins and a second motif present at the calmodulin binding sites of several proteins. Immunofluorescence studies show that the wild-type Asp protein is localized to the polar regions of the spindle immediately surrounding the centrosome. These findings are discussed in relation to the known spindle abnormalities in asp mutants.

Show MeSH
Related in: MedlinePlus