Calmodulin signaling pathways

A special guanylate cyclase receptor can be found in the nitric oxide (NO) signaling pathway. The activation of the sequence of events in that pathway results in smooth muscle relaxation. This pathway is directly linked to other cascades by receiving a Ca2+ signal and utilizing calmodulin (CaM) as transmitter protein. 

Figure 37. Principle of an optical Ca ion sensor based on a calmodulin (CaM)-me-diated Ca signaling pathway and surface plasmon resonance. ...

The signal-mediating function of Ca is performed as a Ca Tcahnodulin complex in many signaling pathways. Ca /catmodulin can bind specifically to effector proteins and modulate their activity. In first place as effector proteins of Ca Tcahnodulin are the /calmodulin protein kinases (CaM kinases) (review Braun and Schuhnan, 1995). The CaM kinases are widespread and are found in practically all cells of mam-... 

With its multiple second messengers and protein kinases, the phosphoinositide signaling pathway is much more complex than the cAMP pathway. For example, different cell types may contain one or more specialized calcium- and calmodulin-dependent kinases with limited substrate specificity (eg, myosin light-chain kinase) in addition to a general calcium- and calmodulin-... 

Furthermore, the LPS signal transduction involves the activation of G proteins, of phospholipases C and D, the formation of diacyl-glycerol (DG) and inositol triphosphate (IP3). DG mediates the stimulation of protein kinase C (PKC) and IP3 induces an increase of cytosolic Ca++ The LPS signaling pathway also involves tyrosine kinases, constitutive nitric oxide (NO) synthase (cNOS), cGMP-dependent protein kinase, Ca channels, calmodulin and calmodulin kinase [27,28], as well as the MAP kinases [29] ERK1, ERK2 and p38 [23], The intracellular events in response to LPS are due to lipid A because they are inhibited by polymyxin B which is known to bind lipid A [27] and they are reproduced by lipids A [30,31]. 

The Ca2+-phosphoinositide signaling pathway. Key proteins include hormone receptors (R), a G protein (G), a phosphoinositide-specific phospholipase C (PLC), protein kinase C substrates of the kinase (S), calmodulin (CaM), and calmodulin-binding enzymes (E), including kinases, phosphodiesterases, etc. (PIP2, phosphatidylinositol-4,5-bisphosphate DAG, diacylglycerol. Asterisk denotes activated state. Open arrows denote regulatory effects.)... 

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