N

FIGURE 10-15 Model of the structural organization of the nucleoporin protein family. The common structural motif diagnostic for nucleoporins is suggested to be a central repetitive domain consisting of many degenerate repeat sequences (which can vary in length) able to fold into short amphipathic /3-sheet structures (wavy line). Apart from this common motif, various members of the nucleoporin protein family are not homologous in the flanking carboxy- and amino-termini, which are involved in their specific function (e.g., NSP1 and NUP1). In the case of yeast NSP1 and human p62, which appear to be functional homologs, the carboxy-terminal domains show a heptad repeat organization and, thus, may form coiled-coil structures (a-helical line). Reproduced with permission from Carmo-Fonseca, M., and Hurt, E. C. (1991). Across the nuclear pores with the help of nucleoporins. Chromosoma 101, 199-205.

FIGURE 10-15 Model of the structural organization of the nucleoporin protein family. The common structural motif diagnostic for nucleoporins is suggested to be a central repetitive domain consisting of many degenerate repeat sequences (which can vary in length) able to fold into short amphipathic /3-sheet structures (wavy line). Apart from this common motif, various members of the nucleoporin protein family are not homologous in the flanking carboxy- and amino-termini, which are involved in their specific function (e.g., NSP1 and NUP1). In the case of yeast NSP1 and human p62, which appear to be functional homologs, the carboxy-terminal domains show a heptad repeat organization and, thus, may form coiled-coil structures (a-helical line). Reproduced with permission from Carmo-Fonseca, M., and Hurt, E. C. (1991). Across the nuclear pores with the help of nucleoporins. Chromosoma 101, 199-205.

10. Adrenal Corticoids cells that have a "receptor" that does not translocate to the nucleus [it probably has an altered DNA-binding site (see the following)] and cells that have a receptor and translocate to the nucleus, but are unresponsive to the hormone. In this last case, which resembles the condition of the late rat fetus, the receptor complex can bind to its acceptor on chromatin, but there is a block in the steps of the receptor mechanism beyond the interaction of receptor and acceptor. The glucocorticoid receptor has a developmental program of its own, and its expression in cells corresponds to the time during development when glucocorticoid responsiveness first appears. This also intersects with the availability of the steroidal ligand secreted from the developing adrenal gland. A molecular analysis of these mutant cells, which have blocks at various points in the receptor mechanism, will help to explain receptor functions. In addition to the types described here, there are also mutations that lead to the rapid degradation of receptor once it has been activated.

The liver enzymes synthesized in response to glucocorticoid action are involved in the metabolism of amino acids or in the synthesis of glycogen and to a limited extent with the synthesis of glucose (Figure 1016). Many of these enzymes are listed in Table 10-1.

B. Glucocorticoids, Analogs, and Antiglucocorticoid Compounds

So far, we have discussed the actions of the major natural glucocorticoids; Cortisol in humans and cortico-sterone in the rat. Other compounds have been synthesized in the laboratory, and some of these have greater potency than the natural hormones. Steroids may be divided into classes, depending on (1) ability to compete for binding to the ligand-binding site of the glucocorticoid receptor and act like glucocorticoids (permit binding to DNA or the cell nucleus compared to the native hormone); (2) ability to bind to the ligand-binding site and permit binding of the ligand-receptor complex to DNA, but to a considerably smaller extent than the natural glucocorticoids; and (3) ability to bind to the glucocorticoid receptor and prevent its binding to DNA in the cell nucleus under activating conditions. Steroids have been classified according to their potency in inducing specific enzymes in cell culture. The enzy-

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Cure Tennis Elbow Without Surgery

Cure Tennis Elbow Without Surgery

Everything you wanted to know about. How To Cure Tennis Elbow. Are you an athlete who suffers from tennis elbow? Contrary to popular opinion, most people who suffer from tennis elbow do not even play tennis. They get this condition, which is a torn tendon in the elbow, from the strain of using the same motions with the arm, repeatedly. If you have tennis elbow, you understand how the pain can disrupt your day.

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