scholarly journals Insulin activates p21Ras and guanine nucleotide releasing factor in cells expressing wild type and mutant insulin receptors.

1993 ◽  
Vol 268 (27) ◽  
pp. 19998-20001
Author(s):  
B Draznin ◽  
L Chang ◽  
J.W. Leitner ◽  
Y Takata ◽  
J.M. Olefsky
Keyword(s):  
Insulin Receptors ◽  
Guanine Nucleotide ◽  
Wild Type ◽  
Mutant Insulin ◽  
In Cells

Insulin inhibition of protein degradation in cells expressing wild-type and mutant insulin receptors

2003 ◽  
Vol 26 (11) ◽  
pp. 1088-1094 ◽  
Author(s):  
F. G. Hamel ◽  
J. Fawcett ◽  
C. I. Andersen ◽  
P. Berhanu ◽  
R. G. Bennett ◽  
...  
Keyword(s):  
Protein Degradation ◽  
Insulin Receptors ◽  
Wild Type ◽  
Insulin Inhibition ◽  
Mutant Insulin ◽  
In Cells

scholarly journals Oligomerization of the Sec7 domain Arf guanine nucleotide exchange factor GBF1 is dispensable for Golgi localization and function but regulates degradation

2016 ◽  
Vol 310 (6) ◽  
pp. C456-C469 ◽  
Author(s):  
Jay M. Bhatt ◽  
Ekaterina G. Viktorova ◽  
Theodore Busby ◽  
Paulina Wyrozumska ◽  
Laura E. Newman ◽  
...  
Keyword(s):  
Guanine Nucleotide Exchange Factor ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Wild Type ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Sec7 Domain ◽  
And Function ◽  
In Cells

Members of the large Sec7 domain-containing Arf guanine nucleotide exchange factor (GEF) family have been shown to dimerize through their NH2-terminal dimerization and cyclophilin binding (DCB) and homology upstream of Sec7 (HUS) domains. However, the importance of dimerization in GEF localization and function has not been assessed. We generated a GBF1 mutant (91/130) in which two residues required for oligomerization (K91 and E130 within the DCB domain) were replaced with A and assessed the effects of these mutations on GBF1 localization and cellular functions. We show that 91/130 is compromised in oligomerization but that it targets to the Golgi in a manner indistinguishable from wild-type GBF1 and that it rapidly exchanges between the cytosolic and membrane-bound pools. The 91/130 mutant appears active as it integrates within the functional network at the Golgi, supports Arf activation and COPI recruitment, and sustains Golgi homeostasis and cargo secretion when provided as a sole copy of functional GBF1 in cells. In addition, like wild-type GBF1, the 91/130 mutant supports poliovirus RNA replication, a process requiring GBF1 but believed to be independent of GBF1 catalytic activity. However, oligomerization appears to stabilize GBF1 in cells, and the 91/130 mutant is degraded faster than the wild-type GBF1. Our data support a model in which oligomerization is not a key regulator of GBF1 activity but impacts its function by regulating the cellular levels of GBF1.

scholarly journals Signal transduction pathways from insulin receptors to Ras. Analysis by mutant insulin receptors.

1994 ◽  
Vol 269 (6) ◽  
pp. 4634-4640
Author(s):  
K. Yonezawa ◽  
A. Ando ◽  
Y. Kaburagi ◽  
R. Yamamoto-Honda ◽  
T. Kitamura ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Insulin Receptors ◽  
Signal Transduction Pathways ◽  
Mutant Insulin

Overexpression of cysteine dioxygenase reduces intracellular cysteine and glutathione pools in HepG2/C3A cells

2007 ◽  
Vol 293 (1) ◽  
pp. E62-E69 ◽  
Author(s):  
John E. Dominy ◽  
Jesse Hwang ◽  
Martha H. Stipanuk
Keyword(s):  
Steady State ◽  
Experimental Evidence ◽  
Cysteine Dioxygenase ◽  
Wild Type ◽  
Hepatic Expression ◽  
Direct Experimental Evidence ◽  
Homeostatic Response ◽  
Catabolic Enzyme ◽  
In Cells

Cysteine levels are carefully regulated in mammals to balance metabolic needs against the potential for cytotoxicity. It has been postulated that one of the major regulators of intracellular cysteine levels in mammals is cysteine dioxygenase (CDO). Hepatic expression of this catabolic enzyme increases dramatically in response to increased cysteine availability and may therefore be part of a homeostatic response to shunt excess toxic cysteine to more benign metabolites such as sulfate or taurine. Direct experimental evidence, however, is lacking to support the hypothesis that CDO is capable of altering steady-state intracellular cysteine levels. In this study, we expressed either the wild-type (WT) or a catalytically inactivated mutant (H86A) isoform of CDO in HepG2/C3A cells (which do not express endogenous CDO protein) and cultured them in different concentrations of extracellular cysteine. WT CDO, but not H86A CDO, was capable of reducing intracellular cysteine levels in cells incubated in physiologically relevant concentrations of cysteine. WT CDO also decreased the glutathione pool and potentiated the toxicity of CdCl2. These results demonstrate that CDO is capable of altering intracellular cysteine levels as well as glutathione levels.

scholarly journals Involvement of Heat Shock Protein 90 in the Degradation of Mutant Insulin Receptors by the Proteasome

1998 ◽  
Vol 273 (18) ◽  
pp. 11183-11188 ◽  
Author(s):  
Takeshi Imamura ◽  
Tetsuro Haruta ◽  
Yasumitsu Takata ◽  
Isao Usui ◽  
Minoru Iwata ◽  
...  
Keyword(s):  
Heat Shock ◽  
Heat Shock Protein ◽  
Insulin Receptors ◽  
Heat Shock Protein 90 ◽  
Mutant Insulin
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