Biomaterial Database

An absolute requirement for the 5' cap structure for mRNA translation in sea urchin eggs. 1983

M M Winkler, and G Bruening, and J W Hershey

Translation of a variety of RNAs was studied in a cell-free translation system derived from sea urchin eggs. While RNAs such as globin or tobacco mosaic virus are efficiently translated, viral RNAs which do not contain the 5' cap structure, such as cow pea mosaic virus (CPMV) and poliovirus, are not translated. Mixing experiments with reticulocyte lysates indicated that the lack of translation of uncapped viral RNAs is not due to the presence of a potent inhibitor or the absence of an activating agent. RNA competition experiments between capped and uncapped RNAs indicated that uncapped RNAs do not interact with the sea urchin egg initiation machinery. Proteolytic removal of the 5' viral protein did not allow the translation of CPMV RNA. However, chemical decapping of vesicular stomatitis virus mRNA completely inhibited the translation of this mRNA in the sea urchin cell-free system. We conclude that the sea urchin egg lacks the initiation pathway used to initiate uncapped mRNAs in mammalian cells and thus has an absolute requirement for the 5' cap structure for initiation. In addition we discuss the implications of these findings for the control of protein synthesis after fertilization of the sea urchin egg.

UI	MeSH Term	Description	Entries
D010063	Ovum	A mature haploid female germ cell extruded from the OVARY at OVULATION.	Egg,Egg, Unfertilized,Ova,Eggs, Unfertilized,Unfertilized Egg,Unfertilized Eggs
D012156	Reticulocytes	Immature ERYTHROCYTES. In humans, these are ERYTHROID CELLS that have just undergone extrusion of their CELL NUCLEUS. They still contain some organelles that gradually decrease in number as the cells mature. RIBOSOMES are last to disappear. Certain staining techniques cause components of the ribosomes to precipitate into characteristic "reticulum" (not the same as the ENDOPLASMIC RETICULUM), hence the name reticulocytes.	Reticulocyte
D002474	Cell-Free System	A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166)	Cellfree System,Cell Free System,Cell-Free Systems,Cellfree Systems,System, Cell-Free,System, Cellfree,Systems, Cell-Free,Systems, Cellfree
D004591	Electrophoresis, Polyacrylamide Gel	Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.	Polyacrylamide Gel Electrophoresis,SDS-PAGE,Sodium Dodecyl Sulfate-PAGE,Gel Electrophoresis, Polyacrylamide,SDS PAGE,Sodium Dodecyl Sulfate PAGE,Sodium Dodecyl Sulfate-PAGEs
D005260	Female		Females
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012315	RNA Caps	Nucleic acid structures found on the 5' end of eukaryotic cellular and viral messenger RNA and some heterogeneous nuclear RNAs. These structures, which are positively charged, protect the above specified RNAs at their termini against attack by phosphatases and other nucleases and promote mRNA function at the level of initiation of translation. Analogs of the RNA caps (RNA CAP ANALOGS), which lack the positive charge, inhibit the initiation of protein synthesis.	RNA Cap,5' Capped RNA,5' mRNA Cap Structure,Cap, RNA,Caps, RNA,RNA, 5' Capped
D012333	RNA, Messenger	RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.	Messenger RNA,Messenger RNA, Polyadenylated,Poly(A) Tail,Poly(A)+ RNA,Poly(A)+ mRNA,RNA, Messenger, Polyadenylated,RNA, Polyadenylated,mRNA,mRNA, Non-Polyadenylated,mRNA, Polyadenylated,Non-Polyadenylated mRNA,Poly(A) RNA,Polyadenylated mRNA,Non Polyadenylated mRNA,Polyadenylated Messenger RNA,Polyadenylated RNA,RNA, Polyadenylated Messenger,mRNA, Non Polyadenylated
D012367	RNA, Viral	Ribonucleic acid that makes up the genetic material of viruses.	Viral RNA
D012617	Sea Urchins	Somewhat flattened, globular echinoderms, having thin, brittle shells of calcareous plates. They are useful models for studying FERTILIZATION and EMBRYO DEVELOPMENT.	Echinoidea,Sand-Dollar,Clypeasteroida,Sand Dollars,Clypeasteroidas,Dollar, Sand,Dollars, Sand,Echinoideas,Sand Dollar,Sand-Dollars,Sea Urchin,Urchin, Sea,Urchins, Sea