Specific macromolecular interactions between tau and the microtubule system

Farías, Gustavo; Vial, Clarisa; Maccioni, Ricardo B.

doi:10.1007/bf00229646

Cited by 20 publications

(7 citation statements)

References 38 publications

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“…In an attempt to identify Drosophila proteins that may interact with functional domains in tubulin, we subjected the larval high-speed supernatants to affinity chromatography using a column filled with ß1I-(422-434)-tubulin peptide covalently coupled to Sepharose . Previous studies have demonstrated the capacity of this ßl1-tubulin fragment from the C-terminal regulatory domain to interact with MAP-2, MAP-4, and T (Maccioni et al ., 1988;Farfas et al ., 1992) . The proteins adsorbed on the affinity column were selectively eluted with 0.5 M NaCl ( Fig .…”

Section: Resultsmentioning

confidence: 99%

DMAP‐85: A τ‐Like Protein from Drosophila melanogaster Larvae

Cambiazo

González

Maccioni

1995

Journal of Neurochemistry

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Microtubule‐associated proteins (MAPs) play major regulatory roles in the organization and integrity of the cytoskeletal network. Our main interest in this study was the identification and the analysis of structural and functional aspects of Drosophila melanogaster MAPs. A novel MAP with a relative molecular mass of 85 kDa from Drosophila larvae was found associated with taxol‐polymerized microtubules. In addition, this protein bound to mammalian tubulin in an overlay assay and coassembled with purified bovine brain tubulin in microtubule sedimentation experiments. The estimated stoichiometry of 85‐kDa protein versus tubulin in the polymers was 1:5.3 ± 0.2 mol/mol. It was shown that the 85‐kDa protein bound specifically to an affinity column of Sepharose‐βII‐(422–434) tubulin peptide, which contains the sequence of the MAP binding domain on βII‐tubulin. Affinity‐purified 85‐kDa protein enhanced microtubule assembly in a concentration‐dependent manner. This effect was significantly decreased by the presence of the βII‐(422–434) peptide in the assembly assays, thus confirming the specificity of the 85‐kDa protein interaction with the C‐terminal domain on tubulin. Furthermore, this protein also exhibited a strong affinity for calmodulin, based on affinity chromatographic assays. Monoclonal and polyclonal anti‐τ antibodies, including sequence‐specific probes that recognize repeated microtubule‐binding motifs on τ, MAP‐2, and MAP‐4 and specific N‐terminal sequences of τ, cross‐reacted with the 85‐kDa protein from Drosophila larvae. These results suggest that τ and Drosophila 85‐kDa protein share common functional and structural epitopes. We have named this protein as DMAP‐85 for Drosophila MAP. The finding on a Drosophila protein with functional homology and structural similarities to mammalian τ opens new perspectives to understand the cellular roles of MAPs.

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Section: Resultsmentioning

confidence: 99%

DMAP‐85: A τ‐Like Protein from Drosophila melanogaster Larvae

Cambiazo

González

Maccioni

1995

Journal of Neurochemistry

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“…Microtubule-associated tau protein was purified from fresh bovine brain, following the procedure of Grundke-Iqbal et al (Grundke-Iqbal et al, 1986) with some modifications (Farias et al, 1992). Brain tissue was homogenized at 4°C in 0.1 M Mes buffer, pH 6.8, 1 M glycerol, 1 mM MgCl 2 in a volume equivalent to tissue weight, in the presence of protease inhibitors (10 g/ml pepstatin, 10 g/ml leupeptin, 100 g/ml PMSF and 1 g/ml aprotinin).…”

Section: Purification Of the Microtubule-associated Tau Proteinmentioning

confidence: 99%

Tau protein binds to pericentromeric DNA: a putative role for nuclear tau in nucleolar organization

Sjöberg

Shestakova

Mansuroglu

et al. 2006

Journal of Cell Science

140

143

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The microtubule-associated tau protein participates in the organization and integrity of the neuronal cytoskeleton. A nuclear form of tau has been described in neuronal and non-neuronal cells, which displays a nucleolar localization during interphase but is associated with nucleolar-organizing regions in mitotic cells. In the present study, based on immunofluorescence, immuno-FISH and confocal microscopy, we show that nuclear tau is mainly present at the internal periphery of nucleoli, partially colocalizing with the nucleolar protein nucleolin and human AT-rich α-satellite DNA sequences organized as constitutive heterochromatin. By using gel retardation, we demonstrate that tau not only colocalizes with, but also specifically binds to, AT-rich satellite DNA sequences apparently through the recognition of AT-rich DNA stretches. Here we propose a functional role for nuclear tau in relation to the nucleolar organization and/or heterochromatinization of a portion of RNA genes. Since nuclear tau has also been found in neurons from patients with Alzheimer's disease (AD), aberrant nuclear tau could affect the nucleolar organization during the course of AD. We discuss nucleolar tau associated with AT-rich α-satellite DNA sequences as a potential molecular link between trisomy 21 and AD.

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“…The microtubular pellets were resuspended in buffer A, and tubulin was puri®ed from the three-cycled microtubular pellets by phosphocellulose chromatography. Tau protein was isolated from brain extracts as described in Farias et al [1992]. MAP-2 was puri®ed as indicated in Vera [1988].…”

Section: Puri®cation Of Proteinsmentioning

confidence: 99%

Tubulin, actin, and tau protein interactions and the study of their macromolecular assemblies

Farías

Muñoz

Garrido

et al. 2002

J of Cellular Biochemistry

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The intracellular polymerization of cytoskeletal proteins into their supramolecular assemblies raises many questions regarding the regulatory patterns that control this process. Binding experiments using the ELISA solid phase system, together with protein assembly assays and electron microscopical studies provided clues on the protein-protein associations in the polymerization of tubulin and actin networks. In vitro reconstitution experiments of these cytoskeletal filaments using purified tau, tubulin, and actin proteins were carried out. Tau protein association with tubulin immobilized in a solid phase support system was inhibited by actin monomer, and a higher inhibition was attained in the presence of preassembled actin filaments. Conversely, tubulin and assembled microtubules strongly inhibited tau interaction with actin in the solid phase system. Actin filaments decreased the extent of in vitro tau-induced tubulin assembly. Studies on the morphological aspects of microtubules and actin filaments coexisting in vitro, revealed the association between both cytoskeletal filaments, and in some cases, the presence of fine filamentous structures bridging these polymers. Immunogold studies showed the association of tau along polymerized microtubules and actin filaments, even though a preferential localization of labeled tau with microtubules was revealed. The studies provide further evidence for the involvement of tau protein in modulating the interactions of microtubules and actin polymers in the organization of the cytsokeletal network.

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Specific macromolecular interactions between tau and the microtubule system

Cited by 20 publications

References 38 publications

DMAP‐85: A τ‐Like Protein from Drosophila melanogaster Larvae

DMAP‐85: A τ‐Like Protein from Drosophila melanogaster Larvae

Tau protein binds to pericentromeric DNA: a putative role for nuclear tau in nucleolar organization

Tubulin, actin, and tau protein interactions and the study of their macromolecular assemblies

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