136 research outputs found
The Rho GDI Rdi1 regulates Rho GTPases by distinct mechanisms
© 2008 by The American Society for Cell Biology. Under the License and Publishing Agreement, authors grant to the general public, effective two months after publication of (i.e.,. the appearance of) the edited manuscript in an online issue of MBoC, the nonexclusive right to copy, distribute, or display the manuscript subject to the terms of the Creative Commons–Noncommercial–Share Alike 3.0 Unported license (http://creativecommons.org/licenses/by-nc-sa/3.0).The small guanosine triphosphate (GTP)-binding proteins of the Rho family are implicated in various cell functions, including establishment and maintenance of cell polarity. Activity of Rho guanosine triphosphatases (GTPases) is not only regulated by guanine nucleotide exchange factors and GTPase-activating proteins but also by guanine nucleotide dissociation inhibitors (GDIs). These proteins have the ability to extract Rho proteins from membranes and keep them in an inactive cytosolic complex. Here, we show that Rdi1, the sole Rho GDI of the yeast Saccharomyces cerevisiae, contributes to pseudohyphal growth and mitotic exit. Rdi1 interacts only with Cdc42, Rho1, and Rho4, and it regulates these Rho GTPases by distinct mechanisms. Binding between Rdi1 and Cdc42 as well as Rho1 is modulated by the Cdc42 effector and p21-activated kinase Cla4. After membrane extraction mediated by Rdi1, Rho4 is degraded by a novel mechanism, which includes the glycogen synthase kinase 3β homologue Ygk3, vacuolar proteases, and the proteasome. Together, these results indicate that Rdi1 uses distinct modes of regulation for different Rho GTPases.Deutsche Forschungsgemeinschaf
Coordination Complexes of Transition Metals (M = Mo, Fe, Rh, and Ru) with Tin(II) Phthalocyanine in Neutral, Monoanionic, and Dianionic States
The
ability of tin atoms to form stable Sn–M bonds with transition
metals was used to prepare transition metal complexes with tin(II)
phthalocyanine in neutral, monoanionic, and dianionic states. These
complexes were obtained via the interactions of [Sn<sup>IV</sup>Cl<sub>2</sub>Pc(3−)]<sup>•–</sup> or [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> radical anions with {Cp*Mo(CO)<sub>2</sub>}<sub>2</sub>, {CpFe(CO)<sub>2</sub>}<sub>2</sub>, {CpMo(CO)<sub>3</sub>}<sub>2</sub>, Fe<sub>3</sub>(CO)<sub>12</sub>, {Cp*RhCl<sub>2</sub>}<sub>2</sub>, or Ph<sub>5</sub>CpRu(CO)<sub>2</sub>Cl. The
neutral coordination complexes of Cp*MoBr(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)]·0.5C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>1</b>) and CpFe(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)]·2C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>2</b>) were obtained
from [Sn<sup>IV</sup>Cl<sub>2</sub>Pc(3−)]<sup>•–</sup>. On the other hand, the coordination of transition metals to [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> yielded anionic
coordination complexes preserving the spin on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>. However, in the case of {cryptand[2,2,2](Na<sup>+</sup>)}{CpFe<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(4−)]}<sup>−</sup>·C<sub>6</sub>H<sub>4</sub>Cl<sub>2</sub> (<b>4</b>), charge transfer from CpFe<sup>I</sup>(CO)<sub>2</sub> to
[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> took place
to form the diamagnetic [Sn<sup>II</sup>Pc(4−)]<sup>2–</sup> dianion and {CpFe<sup>II</sup>(CO)<sub>2</sub>}<sup>+</sup>. The
complexes {cryptand[2,2,2](Na<sup>+</sup>)}{Fe(CO)<sub>4</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>} (<b>5</b>), {cryptand[2,2,2](Na<sup>+</sup>)}{CpMo(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(2−)Sn<sup>II</sup>Pc(3−)<sup>•–</sup>]} (<b>6</b>), and {cryptand[2,2,2](Na<sup>+</sup>)}{Cp*RhCl<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}
(<b>7</b>) have magnetic moments of 1.75, 2.41, and 1.75 μ<sub>B</sub>, respectively, owing to the presence of <i>S</i> = 1/2 spins on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> and CpMo<sup>I</sup>(CO)<sub>2</sub> (for <b>6</b>). In addition,
the strong antiferromagnetic coupling of spins with Weiss temperatures
of −35.5 −28.6 K was realized between the CpMo<sup>I</sup>(CO)<sub>2</sub> and the [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> units in <b>6</b> and the π-stacking {Fe(CO)<sub>4</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}<sub>2</sub> dimers of <b>5</b>, respectively. The [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> radical anions substituted the chloride anions
in Ph<sub>5</sub>CpRu(CO)<sub>2</sub>Cl to form the formally neutral
compound {Ph<sub>5</sub>CpRu<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]} (<b>8</b>) in which the negative charge and
spin are preserved on [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>. The strong antiferromagnetic coupling of spins with a magnetic
exchange interaction <i>J/k</i><sub>B</sub> = −183
K in <b>8</b> is explained by the close packing of [Sn<sup>II</sup>Pc(3−)]<sup>•–</sup> in the π-stacked
{Ph<sub>5</sub>CpRu<sup>II</sup>(CO)<sub>2</sub>[Sn<sup>II</sup>Pc(3−)]<sup>•–</sup>}<sub>2</sub> dimers
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