TY - JOUR
T1 - The G protein β subunit is essential for multiple responses to chemoattractants in Dictyostelium
AU - Wu, Lijun
AU - Valkema, Romi
AU - Van Haastert, Peter J.M.
AU - Devreotes, Peter N.
PY - 1995/6
Y1 - 1995/6
N2 - Increasing evidence suggests that the βγ-subunit dimers of heterotrimeric G proteins play a pivotal role in transducing extracellular signals. The recent construction of Gβ null mutants (gβ-) in Dictyostelium provides a unique opportunity to study the role of dimers in signaling processes mediated by chemoattractant receptors. We have shown previously that gβ- cells fail to aggregate; in this study, we report the detailed characterization of these cells. The gβ- cells display normal motility but do not move towards chemoattractants. The typical GTP-regulated high affinity chemoattractant-binding sites are lost in gβ- cells and membranes. The gβ- cells do not display chemoattractant-stimulated adenylyl cyclase or guanylyl cyclase activity. These results show that in vivo Gβ links chemoattractant receptors to effectors and is therefore essential in many chemoattractant-mediated processes. In addition, we find that Gβ is required for GTPγS stimulation of adenylyl cyclase activity, suggesting that the βγ-dimer activates the enzyme directly. Interestingly, the gβ- cells grow at the same rate as wild-type cells in axenic medium but grow more slowly on bacterial lawns and, therefore, may be defective in phagocytosis.
AB - Increasing evidence suggests that the βγ-subunit dimers of heterotrimeric G proteins play a pivotal role in transducing extracellular signals. The recent construction of Gβ null mutants (gβ-) in Dictyostelium provides a unique opportunity to study the role of dimers in signaling processes mediated by chemoattractant receptors. We have shown previously that gβ- cells fail to aggregate; in this study, we report the detailed characterization of these cells. The gβ- cells display normal motility but do not move towards chemoattractants. The typical GTP-regulated high affinity chemoattractant-binding sites are lost in gβ- cells and membranes. The gβ- cells do not display chemoattractant-stimulated adenylyl cyclase or guanylyl cyclase activity. These results show that in vivo Gβ links chemoattractant receptors to effectors and is therefore essential in many chemoattractant-mediated processes. In addition, we find that Gβ is required for GTPγS stimulation of adenylyl cyclase activity, suggesting that the βγ-dimer activates the enzyme directly. Interestingly, the gβ- cells grow at the same rate as wild-type cells in axenic medium but grow more slowly on bacterial lawns and, therefore, may be defective in phagocytosis.
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U2 - 10.1083/jcb.129.6.1667
DO - 10.1083/jcb.129.6.1667
M3 - Article
C2 - 7790362
AN - SCOPUS:0029020634
SN - 0021-9525
VL - 129
SP - 1667
EP - 1675
JO - Journal of Cell Biology
JF - Journal of Cell Biology
IS - 6
ER -