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gigios85
Nuovo Arrivato
31 Messaggi |
 Inserito il - 07 luglio 2008 : 14:52:35
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Gentilmente Mi fornite due esempi di regolazione genica che implicano il sistema Ca 2+/calmodulina?
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biokiu
Nuovo Arrivato
30 Messaggi |
Inserito il - 07 luglio 2008 : 15:26:44
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dal lodish:
Binding of Ca2 to four sites on calmodulin yields a
complex that interacts with and modulates the activity of
many enzymes and other proteins (see Figure 3-28). Because
Ca2 binds to calmodulin in a cooperative fashion, a small
change in the level of cytosolic Ca2 leads to a large change
in the level of active calmodulin. One well-studied enzyme
activated by the Ca2/calmodulin complex is myosin lightchain
kinase, which regulates the activity of myosin in muscle
cells (Chapter 19). Another is cAMP phosphodiesterase,
the enzyme that degrades cAMP to 5-AMP and terminates
its effects. This reaction thus links Ca2 and cAMP, one of
many examples in which two second messengers interact to
fine-tune certain aspects of cell regulation.
In certain cells, the rise in cytosolic Ca2 following receptor
signaling via PLC-generated IP3 leads to activation of
specific transcription factors. In some cases, Ca2/calmodulin
activates protein kinases that, in turn, phosphorylate
transcription factors, thereby modifying their activity and
regulating gene expression. In other cases, Ca2/calmodulin
activates a phosphatase that removes phosphate groups from
a transcription factor. An important example of this mechanism
involves T cells of the immune system in which Ca2
ions enhance the activity of an essential transcription factor,
NFAT (nuclear factor of activated T cells). In unstimulated
cells, phosphorylated NFAT is located in the cytosol. Following
receptor stimulation and elevation of cytosolic Ca2,
the Ca2/calmodulin complex binds to and activates calcineurin,
a protein-serine phosphatase. Activated calcineurin
then dephosphorylates key phosphate residues on cytosolic
NFAT, exposing a nuclear localization sequence that allows
NFAT to move into the nucleus and stimulate expression of
genes essential for activation of T cells.
The Ca2/calmodulin complex also plays a key role in
controlling the diameter of blood vessels and thus their ability
to deliver oxygen to tissues.
se è per l'esame che penso io, basta! al max rivediti sul libro di fisio la parte muscolare!
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gigios85
Nuovo Arrivato
31 Messaggi |
Inserito il - 07 luglio 2008 : 16:07:26
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| in italiano no è? a quale pag del lodish italiano corrisponde? |
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biokiu
Nuovo Arrivato
30 Messaggi |
Inserito il - 07 luglio 2008 : 17:54:32
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| non so perchè io ce l'ho in inglese! è negli ultimi cpitoli |
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duchè
Utente Attivo
Prov.: ,
1487 Messaggi |
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Topogigio77
Nuovo Arrivato
Città: Milano
37 Messaggi |
Inserito il - 07 luglio 2008 : 18:19:33
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...non voglio credere che noi italiani ancora abbiamo problemi a leggere in inglese...che figura col mondo...  |
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Discussione |
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sistema Ca 2+/calmodulina
Didattica
