The role of soluble GTP binding proteins in the differentiation of adipocytes

点击翻译按钮获取中文摘要

The abundance and the subcellular distribution of GTP-binding proteins was studied in membrance fraction and cytosolic fraction from ST-13 preadipocyte cells before and after differentiation to dexamethazone/isobutylmethylxanthine-sensitive phenotype. After differentiation, the abundance of Gialpha and Gsalpha as detected by immunoblotting with specific antisera was not changed when normalized as per membrane protein. In contrast, Goalpha in membrane as detected by immunoblotting with a specific antiserum against whole Goalpha protein was increased about five-fold after differentiation. ST-13 contains Goalpha, but not Gialpha or Gsalpha in cytosolic fraction and Goalpha in cytosolic fraction also increased to four-fold after differentiation.Antisera against the peptides of Goalpha (22-35) and Goalpha (345-354) recognized the increase of Goalpha in the membrane fraction and cytosolic fraction. Furthermore, pertussis toxin-catalyzed ADP-ribosylation of both membrane and cytosolic fractions in which exogenous betagamma subunits were added was shown to be increased after differentiation, possibly reflecting the increased production of Goalpha in differentiated cells. Antidiabetic agent AD4743 also enhanced adipocyte differentiation of ST-13 cell and Goalpha in membrane and cytosolic fractions was also increased after differentiation. On the other hand, Goalpha in membrane and cytosolic fractions of ST-13 cells which were suppressed to differentiated by retinoic acid was not increased. These results indicate that Goalpha may involve the differentiation of murine preadipocyte ST-13 cells.