Limits...
Dynein, dynactin, and kinesin II's interaction with microtubules is regulated during bidirectional organelle transport.

Reese EL, Haimo LT - J. Cell Biol. (2000)

Bottom Line: Dynein and dynactin bind to microtubules when obtained from cells with aggregated pigment, whereas kinesin II binds to microtubules when obtained from cells with dispersed pigment.Moreover, the microtubule binding activity of these motors/dynactin can be reversed in vitro by the kinases and phosphatase that regulate the direction of pigment granule transport in vivo.These findings suggest that phosphorylation controls the direction of pigment granule transport by altering the ability of dynein, dynactin, and kinesin II to interact with microtubules.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California at Riverside, Riverside, California 92521, USA.

ABSTRACT
The microtubule motors, cytoplasmic dynein and kinesin II, drive pigmented organelles in opposite directions in Xenopus melanophores, but the mechanism by which these or other motors are regulated to control the direction of organelle transport has not been previously elucidated. We find that cytoplasmic dynein, dynactin, and kinesin II remain on pigment granules during aggregation and dispersion in melanophores, indicating that control of direction is not mediated by a cyclic association of motors with these organelles. However, the ability of dynein, dynactin, and kinesin II to bind to microtubules varies as a function of the state of aggregation or dispersion of the pigment in the cells from which these molecules are isolated. Dynein and dynactin bind to microtubules when obtained from cells with aggregated pigment, whereas kinesin II binds to microtubules when obtained from cells with dispersed pigment. Moreover, the microtubule binding activity of these motors/dynactin can be reversed in vitro by the kinases and phosphatase that regulate the direction of pigment granule transport in vivo. These findings suggest that phosphorylation controls the direction of pigment granule transport by altering the ability of dynein, dynactin, and kinesin II to interact with microtubules.

Show MeSH
Dynein, dynactin, and kinesin II remain on pigment granules during bidirectional transport. Immunoblot analysis of purified pigment granules isolated from equal numbers of aggregated (A) or dispersed (D) melanophores and probed with antibodies to dynein (74.1 antibody against dynein intermediate chain), dynactin (p150 antibody against the p150glued subunit), and kinesin II (K2.4 antibody against the 85-kD subunit).
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2189799&req=5

Figure 1: Dynein, dynactin, and kinesin II remain on pigment granules during bidirectional transport. Immunoblot analysis of purified pigment granules isolated from equal numbers of aggregated (A) or dispersed (D) melanophores and probed with antibodies to dynein (74.1 antibody against dynein intermediate chain), dynactin (p150 antibody against the p150glued subunit), and kinesin II (K2.4 antibody against the 85-kD subunit).

Mentions: To determine if the direction of pigment granule transport in Xenopus melanophores is regulated by the cyclic association of microtubule motors with pigment granules, we isolated these organelles from cells that had either aggregated or dispersed pigment. Previous studies have demonstrated that cytoplasmic dynein and kinesin II are present on Xenopus pigment granules (Rogers et al. 1997). Here, we find these motors on the organelles, regardless of whether they have undergone aggregation or dispersion (Fig. 1). In addition, dynactin is also present and at equivalent amounts on granules isolated from melanophores with aggregated or dispersed pigment (Fig. 1). These findings suggest that net attachment or detachment of motors/dynactin to these organelles does not occur as a function of aggregation and dispersion and is not the mechanism regulating the direction of pigment granule transport.


Dynein, dynactin, and kinesin II's interaction with microtubules is regulated during bidirectional organelle transport.

Reese EL, Haimo LT - J. Cell Biol. (2000)

Dynein, dynactin, and kinesin II remain on pigment granules during bidirectional transport. Immunoblot analysis of purified pigment granules isolated from equal numbers of aggregated (A) or dispersed (D) melanophores and probed with antibodies to dynein (74.1 antibody against dynein intermediate chain), dynactin (p150 antibody against the p150glued subunit), and kinesin II (K2.4 antibody against the 85-kD subunit).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2189799&req=5

Figure 1: Dynein, dynactin, and kinesin II remain on pigment granules during bidirectional transport. Immunoblot analysis of purified pigment granules isolated from equal numbers of aggregated (A) or dispersed (D) melanophores and probed with antibodies to dynein (74.1 antibody against dynein intermediate chain), dynactin (p150 antibody against the p150glued subunit), and kinesin II (K2.4 antibody against the 85-kD subunit).
Mentions: To determine if the direction of pigment granule transport in Xenopus melanophores is regulated by the cyclic association of microtubule motors with pigment granules, we isolated these organelles from cells that had either aggregated or dispersed pigment. Previous studies have demonstrated that cytoplasmic dynein and kinesin II are present on Xenopus pigment granules (Rogers et al. 1997). Here, we find these motors on the organelles, regardless of whether they have undergone aggregation or dispersion (Fig. 1). In addition, dynactin is also present and at equivalent amounts on granules isolated from melanophores with aggregated or dispersed pigment (Fig. 1). These findings suggest that net attachment or detachment of motors/dynactin to these organelles does not occur as a function of aggregation and dispersion and is not the mechanism regulating the direction of pigment granule transport.

Bottom Line: Dynein and dynactin bind to microtubules when obtained from cells with aggregated pigment, whereas kinesin II binds to microtubules when obtained from cells with dispersed pigment.Moreover, the microtubule binding activity of these motors/dynactin can be reversed in vitro by the kinases and phosphatase that regulate the direction of pigment granule transport in vivo.These findings suggest that phosphorylation controls the direction of pigment granule transport by altering the ability of dynein, dynactin, and kinesin II to interact with microtubules.

View Article: PubMed Central - PubMed

Affiliation: Department of Biology, University of California at Riverside, Riverside, California 92521, USA.

ABSTRACT
The microtubule motors, cytoplasmic dynein and kinesin II, drive pigmented organelles in opposite directions in Xenopus melanophores, but the mechanism by which these or other motors are regulated to control the direction of organelle transport has not been previously elucidated. We find that cytoplasmic dynein, dynactin, and kinesin II remain on pigment granules during aggregation and dispersion in melanophores, indicating that control of direction is not mediated by a cyclic association of motors with these organelles. However, the ability of dynein, dynactin, and kinesin II to bind to microtubules varies as a function of the state of aggregation or dispersion of the pigment in the cells from which these molecules are isolated. Dynein and dynactin bind to microtubules when obtained from cells with aggregated pigment, whereas kinesin II binds to microtubules when obtained from cells with dispersed pigment. Moreover, the microtubule binding activity of these motors/dynactin can be reversed in vitro by the kinases and phosphatase that regulate the direction of pigment granule transport in vivo. These findings suggest that phosphorylation controls the direction of pigment granule transport by altering the ability of dynein, dynactin, and kinesin II to interact with microtubules.

Show MeSH