Events, biochemical, table

TABLE 5.10 Some Important Biochemical Events in Apoptotic Control ... 

The periodic recurrence of cell division suggests that globally the cell cycle functions like an autonomous oscillator. An extended model incorporating the sequential activation of the various cyclin-dependent kinases, followed by their inactivation, shows that even in the absence of control by cell mass, this sequence of biochemical events can operate as a limit cycle oscillator [145]. This supports the union of the two views of the cell cycle as dominoes and clock [146]. Because of the existence of checkpoints, however, the cell cycle stops at the end of certain phases before engaging in the next one. Thus the cell cycle looks more like an oscillator that slows down and makes occasional stops. A metaphor for such behavior is provided by the movement of the round plate on the table in a Chinese restaurant, which would rotate continuously under the movement imparted by the participants, were it not for frequent stops. 

The caspases that are involved in apoptosis may be further classified as either initiators or effectors. Induction of apoptosis via death receptors results in the activation of an initiator caspase. Caspases-8, -9, and -10 are initiators because they initiate the cascade of biochemical events that culminates in apoptosis. Caspases-3, -6, and -7 propagate this cascade (the so-called doomsday signal), thus functioning as effectors. Although there is some overlap, caspases-1, -4, -5, -11, -12, and -13 are involved in processing cytokines, thus influencing immunoregulation. The various caspases are listed in table 8.2. 

Radioactive decay with emission of particles is a random process. It is impossible to predict with certainty when a radioactive event will occur. Therefore, a series of measurements made on a radioactive sample will result in a series of different count rates, but they will be centered around an average or mean value of counts per minute. Table 1.1 contains such a series of count rates obtained with a scintillation counter on a single radioactive sample. A similar table could be prepared for other biochemical measurements, including the rate of an enzyme-catalyzed reaction or the protein concentration of a solution as determined by the Bradford method. The arithmetic average or mean of the numbers is calculated by totaling all the experimental values observed for a sample (the counting rates, the velocity of the reaction, or protein concentration) and dividing the total by the number of times the measurement was made. The mean is defined by Equation 1.1. 

Methylation is an important biochemical event and all the common purines and their nucleosides occur naturally in mono- or poly-methylated forms. Some common naturally occurring purines are collected in Table 39. 

It is now clear that protein kinase C-catalyzed phosphorylation of specific cellular proteins plays an essential role in the orchestration of the biochemical events responsible for cellular activation. Some of the cellular proteins phosphory-lated by protein kinase C are listed in Table 1. The effects of protein kinase C-mediated phosphorylation include the modulation of ion channels and ion pumps, alterations in cellular endocytosis and exocytosis (e.g., the release of neurotransmitters and humoral agents), and modulation of gene expression and cellular proliferation. 

Genetic and biochemical inhibition studies have highlighted the relationships between the key events of the PPARa activator MOA (Table 17.2). These studies showed that when a key event is inhibited genetically or biochemically, the downstream but not upstream event(s) are inhibited as well. 

Evidence showing the mechanistic linkages between the key events of the MO A is summarized in Table 17.2. Studies that inhibit key events by genetic or biochemical means reveal such relationships because inhibition of one event blocks downstream events. 

At the center of the apoptosis machinery is a family of intracellular proteases, known as caspases (cysteine aspartyl-specific proteases) that are responsible, either directly or indirectly, for the morphological and biochemical events involved in the process Table 1 [6,7]. Recent work has provided evidence that mitochondria also play an important role in... 

Insulin interacts with its cell surface receptor via key amino acid residues located along the N- and C-termini of the A chain of insulin and along the carboxy terminus of the B chain of insulin (Table 32.6). The binding of insulin occurs to amino acid residues located within the N- and C-terminal regions of the a subunit of the receptor, which includes a cysteine-rich region (5). Binding and activation of the insulin receptor results in a cascade of biochemical events previously described. 

Table 9. Morphological and biochemical events associated with different stages of sporulation in Bacillus sp. 

Inflammation can be classified as acute or chrotric (Table 7). Acute irrllammation is the initial response of the body to harmful stimuli and is achieved by the increased movement of PMNLs from the blood into the injured tissues. Then a cascade of biochemical events propagates and matures the (local) inflammatory response. Chronic inflammation usually leads to a progressive shift in the type of immune cells which are present at the site of inflammation and is characterized by destruction and often by (partial) healing of damaged tissues. 

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