G proteins, signal transduction

Van den Ende R, Balink HD, ichel MC, VanZwieten PA. 1994. Influence of ischemia and reperfusion on cardiac signal transduction G protein content, adenylyl cyclase activity, cyclic AMP... 

The signal transduction G-proteins or heterotrimeric GTP binding proteins, are interposed between cell siuface receptors and intracellular effectors. The signal tran uction G-proteins are a family of GTP-binding proteins in which the GTP-GDP switch serves to propagate and amplify regulatory signals from activated cellular membrane receptors to effector channels and enemies. 

See also Kinase Cascade, G Proteins and Signal Transduction, G Proteins in Vision, Kinase Cascade in Fat Mobilization (from Chapter 18)... 

See also Viral and Cellular Oncogenes, Oncogenes in Human Tumors, G Proteins and Signal Transduction, G Protein Families and Subunits, Receptors with Protein Kinase Activity, Hormone Action... 

An, S., Bleu, T. and Zheng, Y., 1999, Transduction of intracellular calcium signals through G protein- mediated activation ofphosphohpase C by recombinant sphingosine 1- phosphate receptors. Mol. Pharmacol. 55 787-794. 

G-protein coupled receptors constitute the largest family of signal transduction membrane proteins. They mediate responses of many bioactive molecules including biogenic amines, amino acids, peptides, lipids, nucleotides and proteins. As a result, GPCRs play a crucial role in many essential physiological processes like neurotransmission, cellular metabolism, secretion, cell growth, immune defense and differentiation. 

Althou the role of the MAP kinase phosphorylation cascade in the control of cell growth and cellular proliferation is undisputed, other pathways and pathway ramifications contribute to that control. This requires communication between signal transduction pathways. MAP kinase also seems to play a part in pathway interconnections, for example in connecting signals from G-protein-coupled receptors with signals from growth-factor-activated receptors (discussed in Chapter 5). 

Keywords G proteins Receptors Signal transduction RGS proteins Effectors GTPase-activating proteins... 

Covalent modification of proteins is a more recently discovered role of fatty acids. Fatty acylation of proteins frequently serves as a means of targeting or anchoring a protein to a membrane. Myristoyla-tion, the addition of 14 0 to a protein, occurs at N-terminal glycine residues after removal of the initiator methionine. This process is generally co-translational and irreversible. N-myristoyl proteins include many signal-transduction-associated proteins, e.g., src and ADP-ribosylation factors. The enzyme N-myristoyltransferase catalyzes the reaction and uses 14 0-CoA as substrate. 

Excitation of smooth muscle via alpha-1 receptors (eg, in the utems, vascular smooth muscle) is accompanied by an increase in intraceUular-free calcium, possibly by stimulation of phosphoUpase C which accelerates the breakdown of polyphosphoinositides to form the second messengers inositol triphosphate (IP3) and diacylglycerol (DAG). IP3 releases intracellular calcium, and DAG, by activation of protein kinase C, may also contribute to signal transduction. In addition, it is also thought that alpha-1 adrenergic receptors may be coupled to another second messenger, a pertussis toxin-sensitive G-protein that mediates the translocation of extracellular calcium. 

---