scholarly journals Inhibition by pertussis toxin of the activation of Na+-dependent uridine transport in dimethyl-sulphoxide-induced HL-60 leukaemia cells

1991 ◽  
Vol 280 (2) ◽  
pp. 515-519 ◽  
Author(s):  
J A Sokoloski ◽  
A C Sartorelli ◽  
R E Handschumacher ◽  
C W Lee
Keyword(s):  
Cholera Toxin ◽  
G Protein ◽  
Pertussis Toxin ◽  
Nucleotide Binding ◽  
Dimethyl Sulphoxide ◽  
Protein G ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding Protein ◽  
Guanine Nucleotide Binding ◽  
Dependent Transport

The effects of pertussis toxin on the Na(+)-dependent transport of uridine were studied in HL-60 leukaemia cells induced to differentiate along the granulocytic or monocytic pathways by dimethyl sulphoxide (DMSO) or phorbol 12-myristate 13-acetate (PMA) respectively. Pertussis toxin at 50 ng/ml completely inhibited the activation of Na(+)-dependent uridine transport and consequently prevented the formation of intracellular pools of free uridine which occurs in HL-60 cells induced to differentiate by DMSO. The inhibition of Na(+)-dependent uridine transport by pertussis toxin in cells exposed to DMSO was associated with a 14-fold decrease in affinity, with no change in Vmax. Pertussis toxin, however, had no effect on Na(+)-dependent uridine transport in PMA-induced HL-60 cells. Furthermore, 500 ng of cholera toxin/ml had no effect on the Na(+)-dependent uptake of uridine in DMSO-treated HL-60 cells. These results suggest that the activation of the Na(+)-dependent transport of uridine in HL-60 cells induced to differentiate along the granulocytic pathway by DMSO is coupled to a pertussis-toxin-sensitive guanine-nucleotide binding protein (G-protein).

Guanine Nucleotide Binding Protein (G Protein), Gamma

2012 ◽  
pp. 831-831
Author(s):  
Thomas E. Meigs ◽  
Alex Lyakhovich ◽  
Hoon Shim ◽  
Ching-Kang Chen ◽  
Denis J. Dupré ◽  
...  
Keyword(s):  
G Protein ◽  
Binding Protein ◽  
Nucleotide Binding ◽  
Protein G ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding Protein ◽  
Guanine Nucleotide Binding ◽  
Nucleotide Binding Protein

scholarly journals GTP analogues promote release of the α subunit of the guanine nucleotide binding protein, Gi2, from membranes of rat glioma C6 BU1 cells

1988 ◽  
Vol 254 (2) ◽  
pp. 391-396 ◽  
Author(s):  
G Milligan ◽  
I Mullaney ◽  
C G Unson ◽  
L Marshall ◽  
A M Spiegel ◽  
...  
Keyword(s):  
G Protein ◽  
Pertussis Toxin ◽  
Nucleotide Binding ◽  
Alpha Subunit ◽  
Guanine Nucleotide ◽  
Guanine Nucleotide Binding Protein ◽  
Rat Glioma ◽  
Glioma C6 ◽  
Gamma Subunits ◽  
Guanine Nucleotide Binding

The major pertussis-toxin-sensitive guanine nucleotide-binding protein of rat glioma C6 BU1 cells corresponded immunologically to Gi2. Antibodies which recognize the alpha subunit of this protein indicated that it has an apparent molecular mass of 40 kDa and a pI of 5.7. Incubation of membranes of these cells with guanosine 5′-[beta gamma-imido]triphosphate, or other analogues of GTP, caused release of this polypeptide from the membrane in a time-dependent manner. Analogues of GDP or of ATP did not mimic this effect. The GTP analogues similarly caused release of the alpha subunit of Gi2 from membranes of C6 cells in which this G-protein had been inactivated by pretreatment with pertussis toxin. The beta subunit was not released from the membrane under any of these conditions, indicating that the release process was a specific response to the dissociation of the G-protein after binding of the GTP analogue. Similar nucleotide profiles for release of the alpha subunits of forms of Gi were noted for membranes of both the neuroblastoma x glioma hybrid cell line NG108-15 and of human platelets. These data provide evidence that: (1) pertussis-toxin-sensitive G-proteins, in native membranes, do indeed dissociate into alpha and beta gamma subunits upon activation; (2) the alpha subunit of ‘Gi-like’ proteins need not always remain in intimate association with the plasma membrane; and (3) the alpha subunit of Gi2 can still dissociate from the beta/gamma subunits after pertussis-toxin-catalysed ADP-ribosylation.

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