Protein synthesis and gene

Protein Synthesis and Gene Expression. Development of the infection structures is accompanied by the synthesis of at least 15 differentiation-related (dr) proteins, i.e. proteins not present in the germling until differentiation is induced Fig. 4 (22. A downshift in the synthesis of some proteins also occurs during infection structure development. 

Some effects of insulin occur within seconds or minutes, including the activation of glucose and ion transport systems, the covalent modification of enzymes (i.e., phosphorylation or dephosphorylation), and some effects on gene transcription (i.e., inhibition of the phosphoenolpyruvate carboxykinase gene). Effects on protein synthesis and gene transcription require hours, while those on cell proliferation and differentiation may take days. 

Heat shock proteins (HSPs) are synthesized by cells in response to an increase in temperature, as well to various other stressful stimuli. Their main function is to ensure intracellular protein homeostasis, thus preserving the cells viability in the presence of aggression. Current evidence points to a protective role for HSPs in several aspects of critical disease, such as ischemia-reperfusion, ARDS, and multiple organ failure. The increase of a few degrees Celsius above the normal environmental temperature of cells leads to the heat shock response 1) rapid expression of heat shock genes, 2) suppression of normal protein synthesis, and 3) the ability of cells to survive a second and otherwise lethal heat challenge (thermotolerance). 

The 20 common amino acids are required in large amounts for protein synthesis, and E. coli can synthesize all of them. The genes for the enzymes needed to synthesize a given amino acid are generally clustered in an operon and are expressed whenever existing supplies of that amino acid are inadequate for cellular requirements. When the amino acid is abundant, the biosyn-... 

Nearly all of the RNA of the cell is synthesized (transcribed) in the nucleus, according to the instructions encoded in the DNA. Some of the RNA then moves out of the nucleus into the cytoplasm where it functions in protein synthesis and in some other ways. Many eukaryotic genes consist of several sequences that may be separated in the DNA of a chromosome by intervening sequences of hundreds or thousands of base pairs. The long RNA transcripts made from these split genes must be cut and spliced in the nucleus to form the correct messenger RNA molecules which are then sent out to the ribosomes in the cytoplasm. 

The gene also includes DNA that is not translated directly into the amino acids of the protein, but is responsible for starting and stopping the process, for regulating the rate of protein synthesis, and for other cellular functions. Doubtless, many such functions remain to be discovered. 

Kamme F. and Wieloch T. (1996) The effect of hypothermia on protein synthesis and the expression of immediate early genes following transientcerebral ischemia. Adv. Neurol. 71,199-206. 

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