Trigger factor

There is evidence that the trigger factor and the hsp70 chaperone DnaK, a PPIase and a secondary amide peptide bond cis-trans isomerase (APIase) respectively, contribute to the formation of native proteins by apparently overlapping functions with the trigger factor as the primary interaction partner of the emerging polypeptide chain [122-124]. Consequently, synthetic lethality was observed 

Both proteins are found to associate with empty or translating ribosomes, and to bind to a certain fraction of newly synthesized polypeptides under normal conditions. Biochemically, DnaK resembles trigger factor in that its APIase activity represents an intrinsic property of the protein chain. For oligopeptide substrates to be catalyzed, neither ATP hydrolysis nor accessory protein factors are necessary. 

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People known to be at risk for anaphylaxis should wear up-to-date medical identification such as a bracelet or other jewelry, or carry an Anaphylaxis Wallet Card listing their confirmed trigger factor(s), relevant co-morbidities such as asthma, and concurrent medications [45]. 

Fig. 7.17 Structure of trigger factor that has been obtained using dipolar coupling data as explained in the two previous figures.

Stress is frequently a trigger factor for depression in vulnerable patients. There is clinical evidence to show that CRT is elevated in the cerebrospinal fluid of untreated depressed patients, which presumably leads to the hypercortisolaemia that usually accompanies the condition. One of the consequences of elevated plasma glucocorticoids is a suppression of some aspects of cellular immunity. It is now established that many cellular (for example, natural killer cell activity, T-cell replication) and non-cellular (for example, raised acute phase proteins) aspects are abnormal in the untreated depressed patient. Such observations could help to explain the susceptibility of depressed patients to physical ill health. 

Entry into and the course of mitosis are primarily determined by the activity of the CDC2 kinase. The CDC2 kinase in the active form exists as a complex with cychn B and, together with the cyclin, forms the mitosis promoting factor, MPF. The activity of MPF oscillates in the cell cycle and is the triggering factor for entry of the cell into M phase. 

Eliminate the cause. Precipitating factors must be recognized and eliminated if possible. These include not only abnormalities of internal homeostasis, such as hypoxia or electrolyte abnormalities (especially hypokalemia or hypomagnesemia), but also drug therapy and underlying disease states such as hyperthyroidism or cardiac disease. It is important to separate this abnormal substrate from triggering factors, such as myocardial ischemia or acute cardiac dilation, which may be treatable and reversible. 

Viral infection is a possible triggering factor. Various viruses are known to be associated with SLE, including myxoviruses, reoviruses, measles, and rubella (A22). The pathogenesis of UVR and viruses in generating autoantibodies will be discussed in a later section. 

Severe and/or persistent AE with unknown trigger factors... 

The discoveries of Csp s and trigger factor may represent the tip of a large iceberg. In view of the pervasive effects of low temperature on the structures of all classes of macromolecules, it is reasonable to conjecture that many more types of proteins will be discovered whose roles are to offset the effects of cold shock on the cell. Some of these molecules may be expressed constitutively and may be part of the normal machinery of the cell. For example, certain ribosomal proteins are thought to function as RNA chaperones, and if present in sufficient amounts, these proteins may allow the cell to cope with the effects of cold shock on the structures of certain classes of RNAs. In yeast, a constitutively expressed ribosomal protein has helicase activity, and mutation in the gene encoding the protein confers on the cells a cold-sensitive phenotype (Schmid and Linder, 1992). Perhaps the apparent absence of cold-induced RNA chaperones in eukaryotic cells is... 

Kandror, O., and A.L. Goldberg (1997). Trigger factor is induced upon cold shock and enhances viability of Escherichia coli at low temperatures. Proc. Natl. Acad. Sci. 94 4978-4981. 

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