Poly -binding protein

Schonfelder, M., Horsch, A. Schmid, H.-P. (1985). Heat shock increases the synthesis of the poly(A)-binding protein in HeLa cells. Proceedings of the National Academy of Sciences, USA, 82, 6884-8. 

Biochemical and genetic experiments in yeast have revealed that the b poly(A) tail and its binding protein, Pablp, are required for efficient initiation of protein synthesis. Further studies showed that the poly(A) tail stimulates recruitment of the 40S ribosomal subunit to the mRNA through a complex set of interactions. Pablp, bound to the poly(A) tail, interacts with eIF-4G, which in turn binds to eIF-4E that is bound to the cap structure. It is possible that a circular structure is formed and that this helps direct the 40S ribosomal subunit to the b end of the mRNA. This helps explain how the cap and poly(A) tail structures have a synergistic effect on protein synthesis. It appears that a similar mechanism is at work in mammalian cells. 

With data obtained by the analysis of fusion proteins consisting of a domain unrelated to poly(3HB) metabolism (e.g., maltose binding protein MalE or glutathione-S-transferase and the poly(3HB) depolymerase binding domain [57,59-61]. 

Kahvejian, A., Svitkin, Y. V., Sukarieh, R., M Boutchou, M. N., and Sonenberg, N. (2005). Mammalian poly(A)-binding protein is a eukaryotic translation initiation factor, which acts via multiple mechanisms. Genes Dev. 19, 104—113. 

Imataka, H., Gradi, A., and Sonenberg, N. (1998). A newly identified N-terminal amino acid sequence of human eIF4G binds poly(A)-binding protein and functions in poly(A)-dependent translation. EMBOJ. 17, 7480-7489. 

Tarun, S. J. J., and Sachs, A. B. (1996). Association of the yeast poly(A) tail binding protein with translation initiation factor eIF4G. EMBOJ. 15, 7168—7177. 

It should be pointed out that the addition of substances, which could improve the biocompatibility of sol-gel processing and the functional characteristics of the silica matrix, is practiced rather widely. Polyethylene glycol) is one of such additives [110— 113]. Enzyme stabilization was favored by formation of polyelectrolyte complexes with polymers. For example, an increase in the lactate oxidase and glycolate oxidase activity and lifetime took place when they were combined with poly(N-vinylimida-zole) and poly(ethyleneimine), respectively, prior to their immobilization [87,114]. To improve the functional efficiency of entrapped horseradish peroxidase, a graft copolymer of polyvinylimidazole and polyvinylpyridine was added [115,116]. As shown in Refs. [117,118], the denaturation of calcium-binding proteins, cod III parvalbumin and oncomodulin, in the course of sol-gel processing could be decreased by complexation with calcium cations. 

Kuhn, U., and Wahle, E. (2004). Structure and function of poly(A) binding proteins. 

Scheuermann, T., Schulz, B., Blume, A., Wahle, E., Rudolph, R., and Schwarz, E. (2003). Trinucleotide expansions leading to an extended poly-L-alanine segment in the poly (A) binding protein PABPN1 cause fibril formation. Protein Sci. 12, 2685-2692. 

Ferro A, Olivera B (1982) Poly(ADP-ribosylation) in vitro. J Biol Chem 257 7808-7813 Gagne JP, Hunter JM, Labrecque B, Chabot B, Poirier GG (2003) A proteomic approach to the identification of heterogeneous nuclear ribonucleoproteins as a new family of poly(ADP-ribose)-binding proteins. Biochem J 371 331-340... 

Gray NK, Coller JM, Dickson KS, Wickens M (2000) Multiple portions of poly(A)-binding protein stimulate translation in vivo. EMBO J 19 4723-4733... 

Uchida N, Hoshino S, Imataka H, Sonenberg N, Katada T (2002) A novel role of the mammalian GSPT/eRE3 associating with poly(A)-binding protein in Cap/Poly(A)-dependent translation. J Biol... 

In vitro experiments show that correct modification of the 3 -end requires at least three protein factors the CPSF protein, the poly-A polymerase and the poly-A binding protein. The CPSF protein (CPSF cleavage and polyadenylation specificity factor) binds to the AAUAA signal and brings the poly-A polymerase to the polyadenylation site. The poly-A polymerase is supported by the poly-A binding protein. The latter binds to the poly-A sequence and is required for the transition from the phase of synthesis of short poly-A sequences to the formation of mature poly-A sequences (ca. 200 A-residues). 

Initiation in Eukaryotic Cells Translation is generally similar in eukaryotic and bacterial cells most of the significant differences are in the mechanism of initiation. Eukaryotic mRNAs are bound to the ribosome as a complex with a number of specific binding proteins. Several of these tie together the 5 and 3 ends of the message. At the 3 end, the mRNA is bound by the poly (A) binding... 

FIGURE 27-22 Protein complexes in the formation of a eukaryotic initiation complex. The 3 and 5 ends of eukaryotic mRNAs are linked by a complex of proteins that includes several initiation factors and the poly(A) binding protein (PAB). The factors elF4E and elF4G are part of a larger complex called elF4F. This complex binds to the 40S ribosomal subunit. 

Poly(A)-agarose Nucleic acids containing poly(U) sequences, mRNA-binding proteins... 

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