Phosphoinositide cascade

As we mentioned earlier, Ca2+ is a component of a number of intracellular signal-transducing pathways, including the phosphoinositide cascade (Figure 11.8). We also mentioned that... 

Figure 11.8 The phosphoinositide cascade. (From Voet and Voet, 2004. Reproduced with permission from John Wiley Sons., Inc.)...

The phosphoinositide cascade is mediated by 7TM receptors and G q proteins. The receptor-triggered activation of... 

G-protein-coupled receptor (GPCR) desensitization (adaptation) protein kinase A (PKA) phosphoinositide cascade phospholipase C protein kinase C (PKC)... 

Figure 14,12 Phosphoinositide cascade. The cleavage of phosphatidyl inositol 4,5-bisphosphate (PIP ) into diacyiglycerol (DAG) and inositol 1,4,5-trisphosphate (IP5) results in the release of calcium ions (due to the opening of the IP3 receptor ion channels) and the activation of protein kinase C (due to the binding of protein kinase C to free DAG in the membrane). Calcium ions bind to protein kinase C and help facilitate its activation.

There are two major types of vasopressin receptors, VI and V2. The VI receptor occurs in vascular smooth muscle and is coupled via to activation of the phosphoinositide cascade-signaling system and generation of the second messenger inositol trisphosphate (IP3) and diacylglycerol. V2 receptors are found in kidney and are coupled via to activation of adenylate cyclase and production of the second messenger cyclic AMP. 

Phosphoinositide cascade The sequence of events that follow the binding of a hormone to a receptor that acts via a Gq-protein. Hormone binding to the Gq-coupled receptor activates phospholipase C, which cleaves PIP2 to IP3 and diacylglycerol, both of which are second messengers. 

Figure 51-1. The phosphoinositide cascade. Binding of hormone to the Gq-coupled receptor leads to the activation of phosphohpase C, which hydrolyzes PIP2 in the membrane to release the two second messengers, DAG and IP3.

Alpha, receptor effects Alpha, receptor effects are mediated primarily by the coupling protein G, which leads to activation of the phosphoinositide cascade and the release of inositol-1,4,5-trisphosphate (IP3) and diacylglycerol (DAG) from membrane lipids. Calcium is subsequently released from stores in smooth muscle cells, and enzymes are activated. Di-... 

Outline the phosphoinositide cascade, and note the diversity of the elicited physiologic responses. 

Describe the biochemical fates of the second messengers produced from PIP2. Note that the phosphoinositide cascade often produces arachidonate—a precursor of the prostaglandin family of hormones. 

Which of the following statements about the phosphoinositide cascade are correct ... 

Which of the following are the second messengers that are produced by the phosphoinositide cascade ... 

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