Purification and properties of protein synthesis initiation and elongation factors from wheat germ

Lax, Sandra R.; Lauer, Stephen J.; Browning, Karen S.; Ravel, Joanne M.

doi:10.1016/0076-6879(86)18068-2

Cited by 116 publications

(93 citation statements)

References 22 publications

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“…The indicated amounts of either nCBP or eIF(iso)4E were added to the reaction mixture containing 20 pmol of eIF(iso)4G. The amount of [ 14 C]leucine incorporated was determined as described previously (20). Capped ␤-globin mRNA was prepared as described (24).…”

Section: Methodsmentioning

confidence: 99%

Identification and Characterization of a Novel Cap-binding Protein from Arabidopsis thaliana

Ruud¹,

Kuhlow²,

Goss³

et al. 1998

Journal of Biological Chemistry

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Cap-binding proteins specifically bind to the 7-methyl guanosine (m 7 G) functional group at the 5 end of eukaryotic mRNAs. A novel Arabidopsis thaliana protein has been identified that has sequence similarity to capbinding proteins but is clearly a different form of the protein. The most obvious primary sequence difference is the substitution of two of the eight conserved tryptophan residues with other aromatic amino acids in the novel protein. Analogous forms of this novel protein appear to be present in other higher eukaryotes but not in yeast. Analysis of the native and recombinant forms of the novel protein by retention on m 7 GTP-Sepharose indicate that it is a functional cap-binding protein. Measurements of the dissociation constant for this protein indicate that it binds m 7 GTP 5-20-fold tighter than eukaryotic initiation factor (eIF)(iso)4E. The novel protein also supports the initiation of translation of capped mRNA in vitro. Biochemical analysis and yeast two-hybrid data indicate that it interacts with eIF(iso)4G to form a complex. Based on these observations, this protein appears to be able to function as a cap-binding protein and is given the designation of novel cap-binding protein (nCBP).Cap-binding proteins (eIF4E) 1 specifically recognize and bind the m 7 G functional group found at the 5Ј end of most eukaryotic cellular mRNAs (for recent reviews, see Refs. 1 and 2). The binding of eIF4E is thought to be the first step in the assembly of several initiation factors on the mRNA prior to the binding of the 40 S ribosome (1-3). One of the structural features of all eIF4E proteins is the presence of eight tryptophan residues in the same relative positions. Recently, the cocrystal structures of the mouse eIF4E (4) and yeast eIF4E (5) with m 7 GDP were solved. Tryptophan residues 3, 5, and 8 were found to be involved in binding the m 7 G functional group (4,5). eIF4E is usually associated with a larger subunit (eIF4G) in a complex named eIF4F (1, 6). eIF4A may also be present in the eIF4E⅐eIF4G complex depending upon the method of purification (7,8). Higher plants possess a unique second form of eIF4F designated eIF(iso)4F (9). eIF(iso)4F contains distinct forms of the cap-binding protein (eIF(iso)4E) and the larger subunit (eIF(iso)4G) (10). The two isoenzyme forms of plant eIF4F have the same activities in vitro (9); however, the eIF(iso)4E prefers hypermethylated caps and mRNAs with less secondary structure (11,12). Recently, a second form of mammalian eIF4G was reported (13). However, this form of eIF4G was not reported to have a distinct form of eIF4E associated with it and does not appear to be the functional equivalent of eIF(iso)4G.The mammalian eIF4E is known to be phosphorylated at Ser-209, and the phosphorylation state appears to correlate with activity of the protein (reviewed in Refs. 14 and 15). Certain stimuli, including insulin and several growth factors, induce phosphorylation of eIF4E (14). Overexpression of the mammalian eIF4E results in cell transformation, suggesting that eIF4E le...

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Section: Methodsmentioning

confidence: 99%

Identification and Characterization of a Novel Cap-binding Protein from Arabidopsis thaliana

Ruud¹,

Kuhlow²,

Goss³

et al. 1998

Journal of Biological Chemistry

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“…The observation that a single subunit from each species is modified by casein kinase II leads us to suggest that the Mr 26 000 subunit of Artemia EF-1 (denoted as/5 in reference [10]) is equivalent to the Mr 33 000 subunit from reticulocytes (denoted as t5 in reference [7]) and the wheat germ polypeptide Mr 36 000 [9]. This subunit would correspond to the low Mr subunit of EF-1 (Table II) which, along with the higher Mr subunit, catalyzes the exchange of GDP bound to EF-lo~ for GTP.…”

Section: Resultsmentioning

confidence: 99%

“…and Traugh, J.A., manuscript in preparation) and Artemia salina [16]. EF-1 /37(6) was purified from Artemia [5] and wheat germ [9]. The factor from Artemia was generously provied by Dr Wim M611er (State University of Leiden, The Netherlands), and the factor from wheat germ was a gift of Dr Joarine M. Ravel (University of Texas, Austin).…”

Section: Methodsmentioning

confidence: 99%

“…The o~-subunit (Mr 50 000) has been isolated alone or in the holoenzyme and mediates the GTP-dependent binding of aminoacyl-tRNA to 80 S ribosomal subunits. The f13" subunits have been isolated [5,8,9] and shown to catalyze the exchange of GDP bound to EF-lot with exogenous GTP. An additional subunit, 6, is sometimes found with the f13' complex and with EF-1; the potential role of 6 in elongation has yet to be realized.…”

Section: Introductionmentioning

confidence: 99%

“…Values were taken from [7] for reticulocytes, from [9] for wheat germ and [5] for Artemia salina. Letters in parentheses denote the nomenclature used in the original paper.…”

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Comparison of phosphorylation of elongation factor 1 from different species by caScin kinase II

1990

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One subunit of EF-I or EF-Ifl7 from Artemia salina, wheat germ and rabbit reticulocytes is modified by casein kinase II. The subunit corresponds to the low Mr subunit of EF-1 (26000-36000) which functions along with a higher Mr subunit (46000~8000), to catalyze the exchange of GDP for GTP on EF-lct. The factor from Artemia and wheat germ is phosphorylated directly on serine by casein kinase II whereas a modulatory compound is required for phosphorylation of EF-1 from reticulocytes. Polylysine increases the rate of phosphorylation of EF-1 from reticulocytes by 24-fold; both serine and threonine are modified. This suggests that polylysine may be substituting for a physiological regulatory compound which modulates phosphoryation in vivo.

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A new candidate protein for high lysine content in wheat grain

Singh

Sharp

Skerritt

2000

J. Sci. Food Agric.

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Purification and properties of protein synthesis initiation and elongation factors from wheat germ

Cited by 116 publications

References 22 publications

Identification and Characterization of a Novel Cap-binding Protein from Arabidopsis thaliana

Identification and Characterization of a Novel Cap-binding Protein from Arabidopsis thaliana

Comparison of phosphorylation of elongation factor 1 from different species by caScin kinase II

A new candidate protein for high lysine content in wheat grain

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