The GTP‐binding regulatory proteins of neuroblastoma × glioma, NG108‐15, and glioma, C6, cells

摘要

>Amounts of the guanine nucleotide binding regulatory proteins which are also pertussis toxin substrates (such as N_i and N_o) were measured in rat glioma, C6BU-1, cells and in neuroblastoma × glioma, NG108-15, hybrid cells. Measurements were performed both by quantitating pertussis toxin catalyzed ADP-ribosylation and by quantitative immunoblotting with affinity purified antibodies specific for N_i or N_o. The amounts of pertussis toxin substrate in C6 and NG108-15 cells are 7.5 and 0.6 data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)80165-X/asset/equation/feb2001457938680165x-math-si1.gif?v=1&s=0263a0f71d46f09bb62b5925d7f461a895011413" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none"> membrane protein, respectively. These levels are minimum values and higher estimates of the total amounts of N proteins in the two cells are obtained by quantitative immunoblot analysis of the β-subunit common to all N proteins. Immunoblots with specific antibodies show that NG108-15 cells contain 3.8 data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)80165-X/asset/equation/feb2001457938680165x-math-si2.gif?v=1&s=084a17a6f680d00d3d9caf89f6e2dca74416fa13" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none"> of N_o and detectable but small ( 0.1 data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)80165-X/asset/equation/feb2001457938680165x-math-si3.gif?v=1&s=055a127b06a94b2eb7ec23e43706c32da87756d6" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none">) amounts of N_i. In contrast, C6 cell membranes contain no detectable N_o and only 0.14 data-equation-construct="true" class="math-equation-construct"> data-equation-image="true" class="math-equation-image"> alt="math formula" src="http://onlinelibrary.wiley.com/store/10.1016/0014-5793(86)80165-X/asset/equation/feb2001457938680165x-math-si4.gif?v=1&s=27e2277f4a7e8c44292534bcc3bfdd7c30f1fd55" class="inlineGraphic" /> data-equation-mathml="true" class="math-equation-mathml" style="display:none"> N_i. Thus, C6 cells contain large amounts of a pertussis toxin substrate which is neither N_i nor N_o.