I n an attempt to determine the RNA-protein interactions involved in the biogenesis of the 50-S ribosomal subunit we have developed a simple and specific system in vitro which reflects some of the intricacies of the Escherichia coli 50-5 subunit. By studying the interaction of isolated ribosomal proteins with 5-5 and 23-S RNAs we have demonstrated the formation of a stable complex which contains 5-S RNA and 23-S RNA and which is dependent upon only two or three ribosomal proteins. The characteristics of this complex have been determined and the responsible proteins identified. The 5-5 -23-5 RNA complex is dependent upon protein L18 in conjunction with either L6 or L25. Although it would be premature to conclude that these results in vitro are directly related to the assembly map in vivo of the 50-S subunit, there is a strong correlation between our results and those obtained with various natural and artificial ribosomal subparticles.The interactions occurring between ribosomal proteins and ribosomal RNA within the intact ribosome appear to be quite complicated and involve linear as well as tridimensional structural information on the part of the RNA. Since the sequential reconstitution of the Escherichia coli 30-5 ribosomal subunit in vitro [l], there has been considerable progress made in understanding some of the RNA-protein interactions involved in both the structure and function offhe 30-S subunit [2--61; however, the larger 50-5 ribosomal subunit of E . coli which contains approximately 34 proteins and two RNA molecules [S], presents a larger problem.There are a few recent experimental reports which discuss the topography and arrangement of the 50-5 ribosomal proteins and RNA while in the complete particle. Most of these studies with E. coli have used either controlled release or partial digestion of the ribosomal proteins [7-91. Studies on the location of ribosomal RNAs within the subunit have proved equally difficult, although one laboratory has tried to localize the protein-binding sites on the 23-S RNA by partial degradation of the 50-S subunit into two fragment particles by cleavage of the 23-5 RNA, and subsequent deterDefinition. A,,, unit, the quantity of material contained in 1 ml of a solution which has an absorbance of 1 at 260 nm, when measured in a 1-cm path-length cell. mination of the protein content of the isolated fragment particles [lo].Another approach to the RNA-protein problem, and the one which we have chosen, is the study of direct interaction of isolated proteins with purified RNAs. It has been shown, using a oneprotein-one-RNA system, that there are only eight 50-5 proteins which are able to bind independently and in equimolar amounts to 23-5 RNA [ll]. These very simple complexes could therefore aid in determining the precise RNA sequences involved in protein-RNA recognition. However, the functionally complete 50-5 contains 5-5 RNA as well and it would be advantageous to study the direct interactions between both RNAs and any proteins necessary for the formation of a complex containi...
The note outlines institutional features of an open outcry market that pennit multiple unit or "block" trades. The purpose of the note is to introduce the process as a tool to be used in economics experiments. The detailed rules governing the multiple unit double auction (MUDA) are stated for the case where offers are tendered by voice as opposed to through a computer. The results of markets that use the rules are reported as a demonstration that convergence to equilibrium price traditionally observed in experimental markets remains with the use of the MUDA process. This note is limited to a discussion of a market instrument which was designed for experimental economics. The institutional features of a new market process are outlined. The process, which is called the multiple unit double auction (MUDA) pennits multiple unit or "block" trades in the framework of a double auction. Because the process allows volume to move faster than the single unit counterparts, it allows researchers greater flexibility in experimental design.The single unit double auction (DA) has been an important tool for the development of an experimental methodology and it has also served as a background "constant" against which institutional influences on market perfonnance could be measured. The MUDA has the same potential as serving as a background process that operates in real t. ime to clear large volumes.Within the traditional DA organization, markets with large volumes 1 and many traders are diffi cult to study. A primary feature of the traditional DA is that both buyers and sellers tender bids and asks for a single unit of the commodity. Such tenders stand until accepted, canceled, or replaced by a better bid or ask. In computerized versions of the traditional double auction, confi nnation of trades is required. Thus, the market proceeds as a series of auctions for single units. In each auction bids ascend and asks decline until a contract (acceptance) occurs. Typically, in an oral double auction market, approximately thirty seconds per unit of equilibrium volume is the time allowed for a market period. The time is cut to a minimum of eight seconds per equilibrium trade in computerized versions with a standby queue. Since each traded unit is accompanied by bids and asks, the time used for trading will vary according to the number of
A consistent observation in particular regions of brains of persons having died with Huntington's disease (HD) is a reduction in the concentration of y-aminobutyric acid (GABA) and a decrease in the activity of its synthetic enzyme, glutamate decarboxylase (EC 4.1.4.15). GABA levels are also reduced in H D cerebrospinal fluids. This study suggests that skin fibroblasts obtained from persons with HD can be used to study their GABA system. A rapid and specific assay for ['4C]glutamate-+ [I4C]GABA based on Aminex A-7 chromatography has been developed. Cell monolayers and homogenates of HD cells convert [14C]glutamate to [14C]GABA. GABA synthesis by HD cell homogenates is pyridoxal dependent and is inhibited by 1 mw-aminooxyacetic acid. GABA synthesis by HD and control cell homogenates also show the same thermal sensitivity as rat brain GAD. When compared to non-HD human cells the H D cells reveal disturbances in the non-neuronal GABA metabolic pathway. Concentrated H D cell homogenates synthesize approx 3 times the amount of GABA as control cells. When diluted both extracts made similar amounts of GABA. Synthesis of GABA by HD cell homogenates is not inhibited by cysteine sulfinate. Decarboxylation of glutamate in these cells is therefore most likely due to glutamate decarboxylase and not cysteine sulfinate decarboxylase. HD cells in monolayer also synthesize 3 times the amount of GABA as compared to control cells. In addition, glutamate upake is altered in H D cells. This report indicates there may be a different pattern of enzyme regulation between H D and control cells.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.