scholarly journals The role of calmodulin-binding sites in the regulation of the Drosophila TRPL cation channel expressed in Xenopus laevis oocytes by Ca2+, inositol 1,4,5-trisphosphate and GTP-binding proteins

1998 ◽  
Vol 333 (3) ◽  
pp. 847-848
Author(s):  
L. LAN ◽  
H. BRERETON ◽  
G. J. BARRITT
Keyword(s):  
Xenopus Laevis ◽  
Binding Sites ◽  
Binding Proteins ◽  
Cation Channel ◽  
Xenopus Laevis Oocytes ◽  
Gtp Binding Proteins ◽  
Calmodulin Binding ◽  
Gtp Binding ◽  
Inositol 1,4,5 Trisphosphate

scholarly journals The role of calmodulin-binding sites in the regulation of the Drosophila TRPL cation channel expressed in Xenopus laevis oocytes by Ca2+, inositol 1,4,5-trisphosphate and GTP-binding proteins

1998 ◽  
Vol 330 (3) ◽  
pp. 1149-1158 ◽  
Author(s):  
Ling LAN ◽  
Helen BRERETON ◽  
J. Greg BARRITT
Keyword(s):  
Binding Sites ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Protein S ◽  
Tryptophan Residue ◽  
Xenopus Laevis Oocytes ◽  
Calmodulin Binding ◽  
Gtp Binding ◽  
Inositol 1,4,5 Trisphosphate ◽  
Stimulation Of

The roles of calmodulin-binding sites in the regulation by Ca2+, inositol 1,4,5-trisphosphate (InsP3) and GTP-binding regulatory proteins (G-proteins) of the Drosophila melanogaster TRPL (transient-receptor-potential-like) non-specific Ca2+ channel were investigated. Wild-type TRPL protein and two mutant forms, TRPL (W713G) and TRPL (W814G), in which a key tryptophan residue in each of the two putative calmodulin-binding sites (Sites 1 and 2, respectively) was replaced by glycine, were expressed heterologously in Xenopuslaevis oocytes. Immunofluorescence studies indicated that the expressed TRPL, TRPL (W713G) and TRPL (W814G) proteins are located at the plasma membrane. TRPL oocytes (oocytes injected with trpl cRNA) and TRPL (W814G) oocytes [oocytes injected with trpl (W814G) cRNA] exhibited substantially greater rates of basal (constitutive) Ca2+ inflow (measured using fluo-3 and the Ca2+ add-back protocol) than mock-injected oocytes (mock oocytes). In TRPL (W713G) oocytes, this difference was abolished. In TRPL and TRPL (W814G) [oocytes injected with trpl (W713G) cRNA], but not in TRPL (W713G) oocytes, basal Ca2+ inflow was inhibited by W13, an inhibitor of calmodulin action. Calmodulin (3 μM intracellular) inhibited basal Ca2+ inflow in TRPL but not in TRPL (W713G) or TRPL (W814G) oocytes. Staurosporin, an inhibitor of protein kinase C (PKC), inhibited, while PMA (an activator of PKC) stimulated, basal Ca2+ inflow in TRPL oocytes. In oocytes incubated in the presence of PMA (to suppress Ca2+ inflow through endogenous receptor-activated Ca2+ channels), the InsP3-induced stimulation of Ca2+ inflow through TRPL channels was more clearly evident than in oocytes incubated in the absence of PMA. InsP3 caused a significant stimulation of Mn2+ inflow in TRPL but not in mock oocytes. Rates of InsP3-stimulated Ca2+ inflow through the TRPL, TRPL (W713G) and TRPL (W814G) channels were similar. The ability of GTPγS to stimulate Ca2+ inflow through TRPL channels was inhibited by 50% in TRPL (W713G) oocytes but was unaffected in TRPL (W814G) oocytes. It is concluded that, in the environment of the Xenopus oocyte, the Drosophila TRPL channel is activated by (a) interaction with Ca2+/calmodulin at calmodulin-binding Site 1; (b) PKC; (c) InsP3 in a process that does not involve Ca2+ and calmodulin; and (d) a trimeric G-protein(s) through both a Ca2+/calmodulin-dependent and a Ca2+/calmodulin-independent mechanism.

scholarly journals The mRNA encoding a β subunit of heterotrimeric GTP-binding proteins is localized to the animal pole of Xenopus laevis oocyte and embryos

1996 ◽  
Vol 59 (2) ◽  
pp. 141-151 ◽  
Author(s):  
Eric Devic ◽  
Laurent Paquereau ◽  
Karine Rizzoti ◽  
Armelle Monier ◽  
Bernard Knibiehler ◽  
...  
Keyword(s):  
Xenopus Laevis ◽  
Binding Proteins ◽  
Xenopus Laevis Oocyte ◽  
Β Subunit ◽  
Animal Pole ◽  
Gtp Binding Proteins ◽  
Gtp Binding

scholarly journals Expression of small GTPases in the roots and nodules of Medicago truncatula cv. Jemalong

2019 ◽  
Vol 78 (1) ◽  
pp. 1-8 ◽  
Author(s):  
Abdul Razaque Memon ◽  
Christiane Katja Schwager ◽  
Karsten Niehaus
Keyword(s):  
Medicago Truncatula ◽  
Binding Proteins ◽  
Polymerase Chain Reaction Analysis ◽  
Small Gtpases ◽  
Infection Process ◽  
Nodule Development ◽  
Gtp Binding Proteins ◽  
Gtp Binding ◽  
Differential Expression Pattern

Abstract In this study we used Medicago truncatula, to identify and analyze the expression of small GTP-binding proteins (Arf1, Arl1, Sar1, Rabs, Rop/Rac) and their interacting partners in the infection process in the roots and nodules. A real-time polymerase chain reaction analysis was carried out and our results showed that Arf1 (AtArfB1c-like), MtSar1, AtRabA1e-like, AtRabC1-like, MsRab11-like and AtRop7-like genes were highly expressed in the nodules of rhizobium inoculated plants compared to the non-inoculated ones. On the contrary, AtRabA3 like, AtRab5c and MsRac1-like genes were highly expressed in non-infected nitrogen supplied roots of M. truncatula. Other Rab genes (AtRabA4a, AtRabA4c and AtRabG3a-like genes) were nearly equally expressed in both treatments. Interestingly, RbohB (a respiratory burst NADPH oxidase homologue) was more highly expressed in rhizobium infected than in non-infected roots and nodules. Our data show a differential expression pattern of small GTP-binding proteins in roots and nodules of the plants. This study demonstrates an important role of small GTP-binding proteins in symbiosome biogenesis and root nodule development in legumes.

Sign in / Sign up

Export Citation Format

Share Document