Diacylglycerol kinase, transmembrane

Partridge AW, Melnyk RA, Yang D, Bowie JU, Deber CM (2003) A transmembrane segment mimic derived from Escherichia coli diacylglycerol kinase inhibits protein activity. J Biol Chem 278 22056-22060... 

Fig. 6.4. Formation and function of diacylglycerol and Ins(l,4,5)P3. Formation of diacylglycerol (DAG) and Ins(l,4,5)P3 is subject to regulation by two central signaling pathways, which start from transmembrane receptors with intrinsic or associated tyrosine kinase activity (see Chapters 8 11) or from G-protein-coupled receptors. DAG activates protein kinase C (PKC, see Chapter 7), which has a regulatory effect on ceU proliferation, via phosphorylation of substrate proteins. Ins(l,4,5)P3 binds to corresponding receptors (InsPs-R) and induces release of Ca from internal stores. The membrane association of DAG, PtdIns(3,4)P2 and PL-C is not shown here, for clarity.

Figure 28-2 Signal transduction by cell-surface receptors that are coupled to G-proteins.Two seven-transmembrane domains, coupled to different G-proteins (Gs, and G,) are shown. Activation of Gs leads to stimulation of the effector enzyme adenylate cyclase and the production of a cAMP second messenger, causing the activation of protein kinase A (PKA) and the initiation of potential phosphorylation cascades. Activation of G leads to stimulation of the effector enzyme phospholipase C p and the production of IP3 and diacylglycerol (DAG) second messengers, one effect of which is to activate protein kinase C (PKC) and Initiate a potential phosphorylation cascade. (From Conn PM.Mefmed S, eds.Textbook of endocrinolog/.Towanta Nj Humana Press 1997.)...

Diacylglycerol is another product of the phosphodiesteratic cleavage of the Inosltides that has recently acquired enhanced importance. 1,2-Diacylglycerol activates a phospholipid- and Ca2+-dependent protein kinase C which is implicated in transmembrane signalling, tumor promotion and cellular differentiation.95,96 1,2-Diacyl-... 

---