Fractionation of the beta subunit common to guanine nucleotide-binding regulatory proteins with the cytoskeleton.

Gs and Gi are guanine nucleotide-binding proteins that mediate the stimulation and inhibition, respectively, of adenylate cyclase. The extent to which the beta subunit common to these proteins may be associated with the cytoskeleton of S49 mouse lymphoma cells was assessed by procedures of differential detergent extraction and immunotransfer blotting. Treatment of cells with 1% Triton X-100 results in nearly quantitative extraction of cellular protein, phospholipid, tubulin, and the catalytic component of adenylate cyclase. Approximately 65% of the beta subunit is refractory to extraction. This population of the beta subunit, along with a population of actin presumed to originate from actin filaments, is subsequently solubilized with hypotonic medium containing 0.5% sodium deoxycholate and 1% Tween-40. The pattern of distribution of the beta subunit among sequential detergent extracts is corroborated by that of generated immunoreactive tryptic fragments. These results are consistent with the interaction of guanine nucleotide-binding proteins with the cytoskeleton.