scholarly journals The role of 5'-leader length, secondary structure and PABP concentration on cap and poly(A) tail function during translation in Xenopus oocytes

2000 ◽  
Vol 28 (15) ◽  
pp. 2943-2953 ◽  
Author(s):  
D. R. Gallie
Keyword(s):  
Secondary Structure ◽  
Xenopus Oocytes ◽  
Tail Function

RNA secondary structure dependence in METTL3–METTL14 mRNA methylation is modulated by the N-terminal domain of METTL3

2020 ◽  
Vol 402 (1) ◽  
pp. 89-98
Author(s):  
Nathalie Meiser ◽  
Nicole Mench ◽  
Martin Hengesbach
Keyword(s):  
Secondary Structure ◽  
Rna Binding ◽  
Specific Protein ◽  
Structure Dependence ◽  
Terminal Domain ◽  
Methylation Assay ◽  
A Site ◽  
Methylation Activity

AbstractN6-methyladenosine (m6A) is the most abundant modification in mRNA. The core of the human N6-methyltransferase complex (MTC) is formed by a heterodimer consisting of METTL3 and METTL14, which specifically catalyzes m6A formation within an RRACH sequence context. Using recombinant proteins in a site-specific methylation assay that allows determination of quantitative methylation yields, our results show that this complex methylates its target RNAs not only sequence but also secondary structure dependent. Furthermore, we demonstrate the role of specific protein domains on both RNA binding and substrate turnover, focusing on postulated RNA binding elements. Our results show that one zinc finger motif within the complex is sufficient to bind RNA, however, both zinc fingers are required for methylation activity. We show that the N-terminal domain of METTL3 alters the secondary structure dependence of methylation yields. Our results demonstrate that a cooperative effect of all RNA-binding elements in the METTL3–METTL14 complex is required for efficient catalysis, and that binding of further proteins affecting the NTD of METTL3 may regulate substrate specificity.

scholarly journals Requirement of mosXe protein kinase for meiotic maturation of Xenopus oocytes induced by a cdc2 mutant lacking regulatory phosphorylation sites.

1992 ◽  
Vol 12 (7) ◽  
pp. 3192-3203 ◽  
Author(s):  
K M Pickham ◽  
A N Meyer ◽  
J Li ◽  
D J Donoghue
Keyword(s):  
Protein Kinase ◽  
Oocyte Maturation ◽  
Xenopus Oocytes ◽  
Germinal Vesicle ◽  
Cyclin B1 ◽  
Phosphorylation Sites ◽  
Germinal Vesicle Breakdown ◽  
Regulatory Phosphorylation

The p34cdc2 protein kinase is a component of maturation-promoting factor, the master regulator of the cell cycle in all eukaryotes. The activity of p34cdc2 is itself tightly regulated by phosphorylation and dephosphorylation. Predicted regulatory phosphorylation sites of Xenopus p34cdc2 were mutated in vitro, and in vitro-transcribed RNAs were injected into Xenopus oocytes. The cdc2 single mutants Thr-14----Ala and Tyr-15----Phe did not induce germinal vesicle breakdown (BVBD) upon microinjection into oocytes. In contrast, the cdc2 double mutant Ala-14/Phe-15 did induce GVBD. Both the Ala-14 and Ala-14/Phe-15p34cdc2 mutants were shown to coimmunoprecipitate cyclin B1 and to phosphorylate histone H1 in immune complex kinase assays. Microinjection of antisense oligonucleotides to c-mosXe was used to demonstrate the role of mos protein synthesis in the induction of GVBD by the Ala-14/Phe-15 cdc2 mutant. Thr-161 was also mutated. p34cdc2 single mutants Ala-161 and Glu-161 and triple mutants Ala-14/Phe-15/Ala-161 and Ala-14/Phe-15/Glu-161 failed to induce GVBD in oocytes and showed a decreased binding to cyclin B1 in coimmunoprecipitations. Each of the cdc2 mutants was also assayed by coinjection with cyclin B1 or c-mosXe RNA into oocytes. Several of the cdc2 mutants were found to affect the kinetics of cyclin B1 and/or mos-induced GVBD upon coinjection, although none affected the rate of progesterone-induced maturation. We demonstrate here the significance of Thr-14, Tyr-15, and Thr-161 of p34cdc2 in Xenopus oocyte maturation. In addition, these results suggest a regulatory role for mosXe in induction of oocyte maturation by the cdc2 mutant Ala-14/Phe-15.

Electronic Transport via Homopeptides: The Role of Side Chains and Secondary Structure

2015 ◽  
Vol 137 (30) ◽  
pp. 9617-9626 ◽  
Author(s):  
Lior Sepunaru ◽  
Sivan Refaely-Abramson ◽  
Robert Lovrinčić ◽  
Yulian Gavrilov ◽  
Piyush Agrawal ◽  
...  
Keyword(s):  
Secondary Structure ◽  
Electronic Transport ◽  
Side Chains

Role of phosphatidylinositide metabolism in ras-induced Xenopus oocyte maturation

1990 ◽  
Vol 10 (3) ◽  
pp. 923-929
Author(s):  
B T Pan ◽  
G M Cooper
Keyword(s):  
Xenopus Oocytes ◽  
Second Messengers ◽  
Phospholipid Metabolism ◽  
Meiotic Maturation ◽  
Ras Oncogene ◽  
Ras Protein ◽  
32P Incorporation ◽  
Kinetics Of ◽  
Oncogene Protein

Microinjection of Xenopus oocytes with ras protein (p21) was used to investigate the role of phospholipid metabolism in ras-induced meiotic maturation. Induction of meiosis by ras was compared with induction by progesterone, insulin, and the phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA). Neomycin, which specifically binds to phosphatidylinositides and inhibits their metabolism, blocked meiotic maturation induced by ras or insulin but not by progesterone or TPA. In addition, p21 and TPA, but not insulin or progesterone, stimulated the incorporation of 32Pi into oocyte lipids. ras protein specifically stimulated 32P incorporation into phosphatidylinositides, whereas both ras and TPA stimulated 32P incorporation into phosphatidylcholine and phosphatidylethanolamine. The stimulatory effect of p21 on phosphatidylinositide metabolism correlated with the dose response and kinetics of ras-induced meiotic maturation. In addition, the ras oncogene protein was more potent than the proto-oncogene protein both in inducing meiotic maturation and in stimulating phosphatidylinositide metabolism. These results indicate that phosphatidylinositide turnover is required for ras-induced meiosis and suggest that phosphatidylinositide-derived second messengers mediate the biological activity of ras in Xenopus oocytes.

Cloning and expression of two plasma membrane aquaporins expressed during the ripening of grape berry

2003 ◽  
Vol 30 (6) ◽  
pp. 621 ◽  
Author(s):  
Sarah Picaud ◽  
Frédéric Becq ◽  
Fabienne Dédaldéchamp ◽  
Agnès Ageorges ◽  
Serge Delrot
Keyword(s):  
Plasma Membrane ◽  
Xenopus Oocytes ◽  
Potential Role ◽  
Grape Berry ◽  
Cloning And Expression ◽  
Vitis Vinifera L ◽  
Moderate Increase ◽  
Grape Berries ◽  
Urea Uptake

The ripening of grape (Vitis vinifera L.) berry is accompanied by dramatic accumulation of sugars and water. Two full-length clones and several partial clones encoding plasma membrane aquaporins (PIP) were cloned from grape berries collected at the beginning of ripening. Based on their sequences, on a phylogenetic analysis and on functional properties, both clones, called VvPIP1a and VvPIP1b were assigned to the PIP1 subfamily. RNA gel blot studies with berries at various stages of development indicated that VvPIP expression was highest at stages following veraison. Injection of Xenopus oocytes with VvPIP1a cRNA induced a moderate increase of water permeability and a large increase in glycerol permeability, whereas injection with VvPIP1b cRNA did not affect these permeabilities. Injection of VvPIP1a cRNA, but not VvPIP1b cRNA, inhibited urea uptake by the oocyte, and this inhibition was sensitive to HgCl2. The data are discussed in relation with the potential role of aquaporins in fruit physiology.

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