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Drosophila roadblock and Chlamydomonas LC7: a conserved family of dynein-associated proteins involved in axonal transport, flagellar motility, and mitosis.

Bowman AB, Patel-King RS, Benashski SE, McCaffery JM, Goldstein LS, King SM - J. Cell Biol. (1999)

Bottom Line: The gene identified by robl encodes a 97-amino acid polypeptide that is 57% identical (70% similar) to the 105-amino acid Chlamydomonas outer arm dynein-associated protein LC7, also reported here.Furthermore, we demonstrate that members of this family of proteins are associated with both flagellar outer arm dynein and Drosophila and rat brain cytoplasmic dynein.We propose that roadblock/LC7 family members may modulate specific dynein functions.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Division of Cellular and Molecular Medicine, Department of Pharmacology, University of California San Diego, La Jolla, California 92093-0683, USA.

ABSTRACT
Eukaryotic organisms utilize microtubule-dependent motors of the kinesin and dynein superfamilies to generate intracellular movement. To identify new genes involved in the regulation of axonal transport in Drosophila melanogaster, we undertook a screen based upon the sluggish larval phenotype of known motor mutants. One of the mutants identified in this screen, roadblock (robl), exhibits diverse defects in intracellular transport including axonal transport and mitosis. These defects include intra-axonal accumulations of cargoes, severe axonal degeneration, and aberrant chromosome segregation. The gene identified by robl encodes a 97-amino acid polypeptide that is 57% identical (70% similar) to the 105-amino acid Chlamydomonas outer arm dynein-associated protein LC7, also reported here. Both robl and LC7 have homology to several other genes from fruit fly, nematode, and mammals, but not Saccharomyces cerevisiae. Furthermore, we demonstrate that members of this family of proteins are associated with both flagellar outer arm dynein and Drosophila and rat brain cytoplasmic dynein. We propose that roadblock/LC7 family members may modulate specific dynein functions.

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Summary of dynein-associated proteins. (A) A complete table of outer dynein arm–associated light chains is shown. The nominal mass refers to the Mr determined by SDS-PAGE analysis; actual predicted mass of the proteins is given parenthetically. Previous work has elucidated biochemical interactions amongst these proteins. (B) A model of cytoplasmic dynein organization is shown. The cytoplasmic dynein particle is built around two heavy chains that form the stems and globular heads of the complex. Associated with the stems are a series of accessory proteins including: two IC74 intermediate chains that mediate dynein–dynactin interactions, two copies of the Tctex1 light chain (or of the related rp3 protein), one dimer of the highly conserved 10 kD/LC8 DLC (LC8 dimer), and a 22-kD polypeptide (the location of which is speculative). The present study indicates that cytoplasmic dynein also contains a robl/LC7-like protein that, by analogy with flagellar outer arm dynein, is located at the base of the dynein particle. A table of known proteins associated with cytoplasmic dynein is given; the majority are conserved in axonemal dyneins.
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Figure 9: Summary of dynein-associated proteins. (A) A complete table of outer dynein arm–associated light chains is shown. The nominal mass refers to the Mr determined by SDS-PAGE analysis; actual predicted mass of the proteins is given parenthetically. Previous work has elucidated biochemical interactions amongst these proteins. (B) A model of cytoplasmic dynein organization is shown. The cytoplasmic dynein particle is built around two heavy chains that form the stems and globular heads of the complex. Associated with the stems are a series of accessory proteins including: two IC74 intermediate chains that mediate dynein–dynactin interactions, two copies of the Tctex1 light chain (or of the related rp3 protein), one dimer of the highly conserved 10 kD/LC8 DLC (LC8 dimer), and a 22-kD polypeptide (the location of which is speculative). The present study indicates that cytoplasmic dynein also contains a robl/LC7-like protein that, by analogy with flagellar outer arm dynein, is located at the base of the dynein particle. A table of known proteins associated with cytoplasmic dynein is given; the majority are conserved in axonemal dyneins.

Mentions: With this report, all the known components of Chlamydomonas outer arm dynein have now been sequenced and a complete list of the properties of outer dynein arm–associated DLCs can be made (Fig. 9 A). The outer dynein arm consists of three heavy chains that form the globular heads and stems of the particle. Each heavy chain is tightly associated with one or more light chains. Located at the base of the structure are two intermediate chains (IC1 and IC2) and several additional light chains including a member of the Tctex1 protein family (LC2) together with multiple copies of the LC8 polypeptide and its homologue LC6. The LC7 protein is not tightly associated with any heavy chain and appears to form part of the intermediate–light chain complex located near the base of the particle (Mitchell and Rosenbaum 1986).


Drosophila roadblock and Chlamydomonas LC7: a conserved family of dynein-associated proteins involved in axonal transport, flagellar motility, and mitosis.

Bowman AB, Patel-King RS, Benashski SE, McCaffery JM, Goldstein LS, King SM - J. Cell Biol. (1999)

Summary of dynein-associated proteins. (A) A complete table of outer dynein arm–associated light chains is shown. The nominal mass refers to the Mr determined by SDS-PAGE analysis; actual predicted mass of the proteins is given parenthetically. Previous work has elucidated biochemical interactions amongst these proteins. (B) A model of cytoplasmic dynein organization is shown. The cytoplasmic dynein particle is built around two heavy chains that form the stems and globular heads of the complex. Associated with the stems are a series of accessory proteins including: two IC74 intermediate chains that mediate dynein–dynactin interactions, two copies of the Tctex1 light chain (or of the related rp3 protein), one dimer of the highly conserved 10 kD/LC8 DLC (LC8 dimer), and a 22-kD polypeptide (the location of which is speculative). The present study indicates that cytoplasmic dynein also contains a robl/LC7-like protein that, by analogy with flagellar outer arm dynein, is located at the base of the dynein particle. A table of known proteins associated with cytoplasmic dynein is given; the majority are conserved in axonemal dyneins.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2199740&req=5

Figure 9: Summary of dynein-associated proteins. (A) A complete table of outer dynein arm–associated light chains is shown. The nominal mass refers to the Mr determined by SDS-PAGE analysis; actual predicted mass of the proteins is given parenthetically. Previous work has elucidated biochemical interactions amongst these proteins. (B) A model of cytoplasmic dynein organization is shown. The cytoplasmic dynein particle is built around two heavy chains that form the stems and globular heads of the complex. Associated with the stems are a series of accessory proteins including: two IC74 intermediate chains that mediate dynein–dynactin interactions, two copies of the Tctex1 light chain (or of the related rp3 protein), one dimer of the highly conserved 10 kD/LC8 DLC (LC8 dimer), and a 22-kD polypeptide (the location of which is speculative). The present study indicates that cytoplasmic dynein also contains a robl/LC7-like protein that, by analogy with flagellar outer arm dynein, is located at the base of the dynein particle. A table of known proteins associated with cytoplasmic dynein is given; the majority are conserved in axonemal dyneins.
Mentions: With this report, all the known components of Chlamydomonas outer arm dynein have now been sequenced and a complete list of the properties of outer dynein arm–associated DLCs can be made (Fig. 9 A). The outer dynein arm consists of three heavy chains that form the globular heads and stems of the particle. Each heavy chain is tightly associated with one or more light chains. Located at the base of the structure are two intermediate chains (IC1 and IC2) and several additional light chains including a member of the Tctex1 protein family (LC2) together with multiple copies of the LC8 polypeptide and its homologue LC6. The LC7 protein is not tightly associated with any heavy chain and appears to form part of the intermediate–light chain complex located near the base of the particle (Mitchell and Rosenbaum 1986).

Bottom Line: The gene identified by robl encodes a 97-amino acid polypeptide that is 57% identical (70% similar) to the 105-amino acid Chlamydomonas outer arm dynein-associated protein LC7, also reported here.Furthermore, we demonstrate that members of this family of proteins are associated with both flagellar outer arm dynein and Drosophila and rat brain cytoplasmic dynein.We propose that roadblock/LC7 family members may modulate specific dynein functions.

View Article: PubMed Central - PubMed

Affiliation: Howard Hughes Medical Institute, Division of Cellular and Molecular Medicine, Department of Pharmacology, University of California San Diego, La Jolla, California 92093-0683, USA.

ABSTRACT
Eukaryotic organisms utilize microtubule-dependent motors of the kinesin and dynein superfamilies to generate intracellular movement. To identify new genes involved in the regulation of axonal transport in Drosophila melanogaster, we undertook a screen based upon the sluggish larval phenotype of known motor mutants. One of the mutants identified in this screen, roadblock (robl), exhibits diverse defects in intracellular transport including axonal transport and mitosis. These defects include intra-axonal accumulations of cargoes, severe axonal degeneration, and aberrant chromosome segregation. The gene identified by robl encodes a 97-amino acid polypeptide that is 57% identical (70% similar) to the 105-amino acid Chlamydomonas outer arm dynein-associated protein LC7, also reported here. Both robl and LC7 have homology to several other genes from fruit fly, nematode, and mammals, but not Saccharomyces cerevisiae. Furthermore, we demonstrate that members of this family of proteins are associated with both flagellar outer arm dynein and Drosophila and rat brain cytoplasmic dynein. We propose that roadblock/LC7 family members may modulate specific dynein functions.

Show MeSH
Related in: MedlinePlus