Prostaglandin E1 receptor from mouse mastocytoma P-815 cells couples to 60 kDa GTP-binding protein.

The stable 3H]prostaglandin E1 (PGE1)-bound receptor, which couples to 60 kDa GTP-binding protein, from membranes of mouse mastocytoma P-815 cells has been purified and characterized. When the membranes were preincubated with 3H]PGE1 for 60 min at 37 degrees C, the dissociation of the ligand from the receptor was remarkably decreased, even in the presence of GTP gamma S. The stable 3H]PGE1-bound receptor complex was solubilized with 6% digitonin. The solubilized 3H]PGE1 receptor was eluted with 35S]GTP gamma S bindings activity from an Ultrogel AcA44 column. The fractions containing activities of both 3H]PGE1 and 35S]GTP gamma S bindings were further purified by column chromatographies on wheat germ agglutinin (WGA)-agarose and phenyl-Sepharose CL-4B. The partially purified 3H]PGE1-bound receptor was affinity-labeled with 14C]5'-p-fluorosulfonylbenzoylguanosine and a protein with a molecular mass of 60 kDa was detected. These results suggest that the ligand-bound PGE1 receptor of P-815 cells associates with a novel GTP-binding protein with a molecular mass of 60 kDa.