Quality control mechanisms

Ultrapure water To achieve this MU water grade requires the use of several special process features and quality control mechanisms chosen from a wide array of technology tools. Routes chosen may include the provision of UF both pre- and postpurification, carbon... 

Dittrich R, Ritter M, Kaps M, Sieber M, Lees K, Lamie V, Nabavi D, Ringelstein E, Markus H, Droste D. The use of embolic signal detection in multicenter trials to evaluate antiplatelet efficacy signal analysis and quality control mechanisms in the CARESS trial. Stroke 2006 37 1065-1069. 

Good science exists in research in academic institutions apart from the soon to be established Environmental Protection Agency s (EPA) Good Laboratory Practice (GLP) guidelines. However, this is not to say that GLP s are not advisable. Good science should be able to stand up to review as having been performed using appropriate and adequate laboratory practices. Scientists have had their work routinely scrutinized by their peers for its quality and will not resent careful analysis by others. For example, only a portion of the work produced by the scientific community is acceptable for publication in its various journals. The rate of acceptance in journals varies but it is apparent that the peer review system attempts to serve as a quality control mechanism in the scientific community. 

Calnexin and its soluble homologous calreticulin belong to the family of lectinlike chaperones. Their task is to interact with the partially trimmed monoglycosy-lated N-linked oligosaccharides and therefore contribute to an important part of the maturation and quality control mechanisms of glycoproteins [72]. The expression... 

Vitale, A. and Ceriotti,A. (2004) Protein quality control mechanisms and protein storage in the endoplasmic reticulum. A conflict of interests Plant Physiol. 136, 3420-3426. 

M. Ibba and D. Soli. 1999. Quality control mechanisms during translation Science 286 1893-1897. (PubMed)... 

Fig. 4. A model for the involvement of calnexin in quality control mechanism in ER. Association and disengagement of calnexin depend on the folding status of the semiprocessed glycoprotein. Calnexin recognizes partially trimmed monoglucosylated glycans, generated either by glucose trimming or by reglucosylation pathways. Symbols and abbreviations are same as Fig. 3 (adopted from [45])...

The refolding and degradation of proteins and the role of chaperones and proteases in protein folding are ana-lyzed. The triage model describes the quality control mechanism within the human body. The mechanism describes the fate of an unfolded protein, which may fold either to the native state or form the aggregate. The protein that tends to misfold may bind with the chaperone. This undergoes protein remodeling and is mixed with the pool of unfolded and misfolded proteins as shown in Fig. 5. 

In both procedures, a gene encoding an abundant membrane glycoprotein (G protein) from vesicular stomatitis virus (VSV) Is Introduced Into cultured mammalian cells either by transfection or simply by Infecting the cells with the virus. The treated cells, even those that are not specialized for secretion, rapidly synthesize the VSV G protein on the ER like normal cellular secretory proteins. Use of a mutant encoding a temperature-sensitive VSV G protein allows researchers to turn subsequent protein transport on and off. At the restrictive temperature of 40 °C, newly made VSV G protein Is misfolded and therefore retained within the ER by quality control mechanisms discussed in Chapter 16, whereas at the permissive temperature of 32 C, the accumulated... 

Mutant proteins, those incorrectly folded, are flagged by the cell s quality control mechanism and destined either for destruction or reprocessing (Figure 3.8.3). Terminally misfolded proteins are marked by the addition of many copies of a small protein called ubiquitin, and are then digested into fragments by proteasomes. 

One of many characteristics of misfolded proteins is the presence of hydrophobic portions on their surfaces normally only hydrophilic portions appear on the outside. The problem is that the cell s quality control mechanism relies on chemical, not functional, tests. Thns, a protein labeled for destruction or reprocessing may actually be functionally equivalent or superior to a normal protein. 

Describe a hypothetical process that intervenes in the body s natural protein quality-control mechanism to improve health. 

The effects and value of quality control are fer-reaching, and the absence or feilure of quality control has equally far-reaching consequences. One can readily imagine the economic costs if the dependability of products were to decline. The cost per unit produced would rise as the proportion of unusable products increased. In the marketplace, more products would prove to be defective or fail, resulting in greater repair and replacement costs for the producer and consumer. If quality-control mechanisms affected service, resulting in less effective services, consumer satisfaction would also decline. Quality-control procedures most likely will become an increasingly prominent component of production as more effective methods are developed. 

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