The GPQ-Rich Segment of Dictyostelium Myosin IB Contains an Actin Binding Site

Rosenfeld, Steven S.; Rener, Brenda

doi:10.1021/bi00174a045

Cited by 45 publications

(37 citation statements)

References 29 publications

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“…First, the TH1 membrane-binding region has been shown to interact with F-actin in the presence of ATP (37,39). Second, the TH2 region (ATP-independent actin-binding region, or GPA/Q domain) binds actin in vitro (27,58) and in Saccharomyces cerevisiae assists in the formation of actin-patch-like structures on glass beads (25). Third, the SH3 domain within TH2 and the S. cerevisiae myosin I-specific C-terminal acidic (A) region are required for indirect interactions of myosin I with actin.…”

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confidence: 99%

Functional Characterization of Myosin I Tail Regions in Candida albicans

et al. 2004

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The molecular motor myosin I is required for hyphal growth in the pathogenic yeast Candida albicans. Specific myosin I functions were investigated by a deletion analysis of five neck and tail regions. Hyphal formation requires both the TH1 region and the IQ motifs. The TH2 region is important for optimal hyphal growth. All of the regions, except for the SH3 and acidic (A) regions that were examined individually, were required for the localization of myosin I at the hyphal tip. Similarly, all of the domains were required for the association of myosin I with pelletable actin-bound complexes. Moreover, the hyphal tip localization of cortical actin patches, identified by both rhodamine-phalloidin staining and Arp3-green fluorescent protein signals, was dependent on myosin I. Double deletion of the A and SH3 domains depolarized the distribution of the cortical actin patches without affecting the ability of the mutant to form hyphae, suggesting that myosin I has distinct functions in these processes. Among the six myosin I tail domain mutants, the ability to form hyphae was strictly correlated with endocytosis. We propose that the uptake of cell wall remodeling enzymes and excess plasma membrane is critical for hyphal formation.

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confidence: 99%

Functional Characterization of Myosin I Tail Regions in Candida albicans

et al. 2004

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“…In the known myosin-I sequences, the SH3 domain invariably resides in tandem with one or two proline-rich domains (5,9); a proline-rich sequence of 3BP1 has been identified as a motif that binds to the SH3 domain of Abl (10). An interaction has not been demonstrated between SH3 and proline-rich domains of myosin-I, but proline-rich domains of myosin-I have been shown to interact with actin (11)(12)(13). These results suggested to us that the SH3 domain of myosin-I might be available for interaction with another protein.…”

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confidence: 99%

Identification of Acan125 as a Myosin-I-binding Protein Present with Myosin-I on Cellular Organelles of Acanthamoeba

Zot

1995

Journal of Biological Chemistry

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We have discovered the first protein to bind to a nonfilamentous myosin, aside from actin. This protein, Acan125, is a 125-kDa protein from Acanthamoeba that associates with the SH3 domain of Acanthamoeba myosin-IC and not the SH3 domain of human fodrin. Antibodies raised against Acan125 recognize a single protein of 125 kDa from a whole cell lysate of Acanthamoeba; antibodies to myosin-I (M1.7 and M1.8) do not recognize Acan125 on the same blot. Double labeling of Acanthamoeba show Acan125 and myosin-I to be present on the same intracellular organelle, most likely amoebastomes. Immunoprecipitation with either anti-myosin-I or anti-Acan125 antibodies coprecipitates both Acan125 and myosin-I from a lysate of Acanthamoeba, demonstrating that Acan125 interacts with native myosin-I.Binding through the Src homology domain, SH3, 1 is a recognized means of linking signal transduction proteins (1-3), but a function has not been ascribed to the SH3 domain of the cytoskeletal protein myosin-I. The isoforms of myosin-I that contain an SH3 domain include myosin-Is from Acanthamoeba (4), Dictyostelium (5), Saccharomyces (6), rat (7), and human (8). In the known myosin-I sequences, the SH3 domain invariably resides in tandem with one or two proline-rich domains (5, 9); a proline-rich sequence of 3BP1 has been identified as a motif that binds to the SH3 domain of Abl (10). An interaction has not been demonstrated between SH3 and proline-rich domains of myosin-I, but proline-rich domains of myosin-I have been shown to interact with actin (11-13). These results suggested to us that the SH3 domain of myosin-I might be available for interaction with another protein.The proposal of proteins that interact with myosin-I is rooted in efforts to reconcile reconstitution results with cellular localization studies. In vitro binding (11,14,15) and motility (16) assays are consistent with myosin-I acting mechanically on the surface of any membrane containing the ubiquitous phospholipid phosphatidylserine. But immunostaining shows myosin-I to be excluded from most cell membranes and to be concentrated at the leading edges of migrating cells (17, 18) and on selected organelles (19). The contractile vacuole of Acanthamoeba has been demonstrated to selectively bind the myosin-IC isoform (20). Myosin-IA and myosin-IB were found, using immunogold, to be associated along one side of fractionated membranes (21), as though bound to proteins.Myosin-I could associate with other proteins on membrane surfaces via interactions with SH3. SH3 domains have been shown to mediate specific associations between SH3-containing proteins and various binding partners, including phosphatidylinositol 3-kinase (22-25), p22 phox , and p47phox (26 -28), and dynamin (29 -31). In each of these studies, bacterially expressed fusion proteins of SH3 domains were used as affinity ligands to selectively extract the binding partner from a cell lysate. Selectivity may be dictated by the structures of both the SH3 domain and its binding partner (32,33). Thus, binding partners fo...

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“…The amino acid composition of TH2 (also called GPA or GPQ) is highly biased towards Gly, Pro, and basic residues such as Lys (in myoC) or Arg, as well as to a lesser degree towards Ala (in myoC and myoD) or Gin (myoB). This domain has been shown to serve as an ATP-independent secondary actin-binding site (56,57). In good agreement with the presence of both membrane-and actin-binding sites, myoB, myoC, and myoD have been localized at the cortex of vegetative cells and at the leading edge of motile D. discoideum cells during chemotaxis (13,(71)(72)(73)(74).…”

Section: Structure/function Analysismentioning

confidence: 68%

“…Some stretches have a high propensity to form a coiled-coil, which is proposed to induce the formation of dimers. In myosin Is, the tail homology I (TH1) domains were shown to have high-affinity phospholipid-binding sites (54,55), whereas the TH2 domains possess ATP-independent actin binding sites (56,57). A domain found in the tail of myosin VII and X has high homology to the membrane-binding domain of the talin/Band-4.1 family proteins.…”

Section: Myosins Are Tripartite Modular Motorsmentioning

confidence: 99%

Unconventional myosins at the crossroad of signal transduction and cytoskeleton remodeling

1999

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The cytoplasm of eukaryotic cells is a very complex milieu and unraveling how its unique cytoarchitecture is achieved and maintained is a central theme in modern cell biology. It is crucial to understand how organelles and macro-complexes of RNA and/or proteins are transported to and/or maintained at their specific cellular locations. The importance of filamentous-actindirected myosin-powered cargo transport was only recently realized, and after an initial explosion in the identification of new molecules, the field is now concentrating on their functional dissection. Direct connections of myosins to a variety of cellular tasks are now slowly emerging, such as in cytokinesis, phagocytosis, endocytosis, polarized secretion and exocytosis, axonal transport, etc. Unconventional myosins have been identified in a wide variety of organisms, making the presence of actin and

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The GPQ-Rich Segment of Dictyostelium Myosin IB Contains an Actin Binding Site

Cited by 45 publications

References 29 publications

Functional Characterization of Myosin I Tail Regions in Candida albicans

Functional Characterization of Myosin I Tail Regions in Candida albicans

Identification of Acan125 as a Myosin-I-binding Protein Present with Myosin-I on Cellular Organelles of Acanthamoeba

Unconventional myosins at the crossroad of signal transduction and cytoskeleton remodeling

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