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UCSD study reveals the regulatory mechanism of key enzyme
September 21, 2007
Protein kinase A involved in cardiac disease and breast cancer Research conducted at the University of California, San Diego (UCSD) School of Medicine has shed new light on the structure and function of one of the key proteins in all mammalian cells, protein kinase A (PKA), an enzyme which plays an essential role in memory formation, communication between nerve cells, and cardiac function.
Utilizing a process called x-ray crystallography, the scientists solved the structure of the large PKA complex, revealing a totally new structure that shows PKA's amazing ability to function as a "scaffold," that supports and controls the release of chemicals involved in transmitting signals. The structure is shown in the September 21 issue of the journal Cell, featuring the study that describes the dynamic regulatory subunit of PKA.
PKA belongs to a large superfamily of proteins whose activity is regulated by an important small molecule, cyclic AMP (cAMP), in the cell. Protein kinases transmit chemical signals within the cell to regulate a host of functions, such as cell growth or metabolism. Certain protein kinases have been implicated in the uncontrolled growth of cells; for example, when PKA somehow stays "on," its prolonged activation can lead to cardiac disease and breast cancer.
By revealing its highly accurate three-dimensional structure, the UCSD scientists have shown how PKA is inhibited and activated by cAMP. PKA contains two components, the regulatory and catalytic subunits. When the subunits are together in the absence of cAMP, the signaling is turned off; when the two parts break apart after being activated by cAMP, PKA is turned on.
"We knew how the two subunits, the catalytic and regulatory subunits, looked as separate entities. But we didn't understand how they actually fit together and are activated by cAMP until we saw this structure," said Susan Taylor, Ph.D., Howard Hughes Medical Institute Investor and professor of pharmacology at UCSD School of Medicine, who headed the study.
Discovery of this enzyme's molecular structure may help researchers to design drugs that specifically block the protein kinase activity involved in cancer or cardiac disease.
"Scientists didn't really understand how the structure unfolded before now," said Taylor, adding that preventing the subunits from coming apart may be an effective way to inhibit diseases caused when PKA is activated and can't turn itself off. Taylor said the researchers were surprised at how much the structure changed when PKA is turned off. "The regulatory subunit opens up and literally wraps itself around the catalytic subunit, thus completely turning the signal off," she said.
Taylor is one of the world's leading experts on the cAMP-dependent protein kinase, an enzyme that serves as a prototype for the entire protein kinase family. This family of enzymes has more than 500 members that are critical for regulation in all multi-cellular organisms, such as humans.
Taylor's work in 1991 (reported in the July 26, 1991 issue of the journal Science) revealed the first-ever molecular structure of the catalytic subunit of a protein kinase, one involved in the action of adrenalin within cells. Understanding its structure was a sort of Rosetta stone for learning the structure of all protein kinases, because they all share certain fundamental characteristics.
University of California - San Diego
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Kinase Inhibitor Drugs (Wiley Series in Drug Discovery and Development)
by Rongshi Li (Author), Jeffrey A. Stafford (Author)
A comprehensive resource on case studies of marketed kinase drugs and promising drug trials Since the discovery of protein kinase activity in 1954, the field of protein kinase drug discovery has advanced dramatically. With the ongoing clinical success of the Bcr-Abl kinase inhibitor Gleevec in the treatment of chronic myelogenous leukemia and seven additional marketed kinase inhibitor drugs, researchers have compelling evidence that kinase inhibitors can be highly efficacious in the treatment of diseases caused by aberrant activity of protein kinase. Currently more than 100 protein kinase inhibitors are in clinical development. In one comprehensive volume, the editors, Dr. Rongshi Li and Dr. Jeffrey Stafford, present timely and important case studies of marketed...
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Protein Kinase Protocols (Methods in Molecular Biology)
by Alastair D. Reith (Editor)
GlaxoSmithKline, Essex, UK. Presents a range of techniques and tools for understanding the roles of specific protein kinases within signalling cascades and for identification and evaluation of novel therapeutic targets. For researchers.
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Jarrow - Creatine Monoydrate, 600 gm 600 gms
by Jarrow Formulas
Creatine is synthesized in the liver from the amino acidsarginine and glycine and stored in the major muscles, including cardiac and skeletal tissues. Once inside the muscle, creatine is phosphorylated to form creatine phosphate (CP), a high energy substrate that assists in the contraction of the myofibrils (muscle fibers). Creatine Phosphate is utilized to maintain higher levels of ATP (energy molecules) during exercise. Creatine Phosphate maximizes physical performance and reduces exercise fatigue by absorbing hydrogen ions released by muscles in the form of lactic acid. Intense anaerobic exercise, such as weight lifting and sprinting, depletes ATP and greatly increases the demand for creatine.
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Protein Tyrosine Kinases: From Inhibitors to Useful Drugs (Cancer Drug Discovery and Development)
by Doriano Fabbro (Editor), Frank McCormick (Editor)
Leading researchers, from the Novartis group that pioneered Gleevec/Glivec™ and around the world, comprehensively survey the state of the art in the drug discovery processes (bio- and chemoinformatics, structural biology, profiling, generation of resistance, etc.) aimed at generating PTK inhibitors for the treatment of various diseases, including cancer. Highlights include a discussion of the rationale and the progress made towards generating "selective" low molecular-weight kinase inhibitors; an analysis of the normal function, role in disease, and application of platelet-derived growth factor antagonists; and a summary of the factors involved in successful structure-based drug design. Additional chapters address the advantages and disadvantages of in vivo preclinical models for...
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Glycogen Synthase Kinase 3 (GSK-3) and Its Inhibitors: Drug Discovery and Development (Wiley Series in Drug Discovery and Development)
by Ana Martinez (Editor), Ana Castro (Editor), Miguel Medina (Editor), Binghe Wang (Editor)
Many researchers believe that GSK-3 and its inhibitors could lead to effective treatments for neurogenerative disorders, type II diabetes, depression and bipolar disorder, and some forms of cancer. This book provides a thorough introduction to GSK-3, presents up-to-date information, and mentions the birth of several chemical families of GSK-3 inhibitors with varying selectivity. It’s a great reference for researchers in drug design and development.
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Protein Kinase Functions
by Jim Woodgett (Editor)
Ontario Cancer Institute, Toronto, Canada. Compilation of recent findings in the field and designed to enable the reader to assimilate, compare, and integrate the molecular machinery used by cells to coordinate and respond to their environments. Previous edition: c1994. Softcover, hardcover also available.
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The Protein Kinase Factsbook, Two-Volume Set, Volume 1-2: Protein-Tyrosine Kinases
by Grahame Hardie (Author), Steven Hanks (Author)
How do you keep track of basic information on the proteins you work with? Where do you find details of their physicochemical properties, amino acid sequences, gene organization? Are you tired of scanning review articles, primary papers and databases to locate that elusive fact? The Academic Press FactsBook series will satisfy scientists and clinical researchers suffering from information overload. Each volume provides a catalogue of the essential properties of families of molecules. Gene organization, amino acid sequences, physicochemical properties, and biological activity are presented using a common, easy to follow format. Taken together they compile everything you wanted to know about proteins but were too busy to look for. The Protein Kinase FactsBook: Protein - Tyrosine...
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Protein Kinase Inhibitors, Volume 480
by Kevan Shokat (Editor)
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Protein Kinase C (Molecular Biology Intelligence Unit)
by Lodewijk V. Dekker (Editor)
Protein Kinase C is a pivotal component of the mechanism that allows a cell to respond to its changing environment. In this book, the most significant advances in recent basic research on Protein Kinase C are explained by active researchers in the field. The first seven chapters provide a comprehensive account of the fundamental structural and biochemical properties of Protein Kinase C. The remaining chapters contain overviews of the function of Protein Kinase C, both in lower organisms and in mammalian cells, the latter with a focus on immune cells and nerve cells. This book is the only recent publication devoted entirely to Protein Kinase C and forms a major point of reference for those active in the field. In addition it will appeal to those with a general interest in biochemistry,...
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Creatine Kinase (Molecular Anatomy and Physiology of Proteins)
by Christian Vial (Editor)
Creatine kinases and arginine kinases are an historical model in enzymology. They belong to the large family of phosphagen kinases which transfer a phosphoryl group from ATP to a nitrogen atom within a guanidinium group to form, what was called by the early muscle physiologists, a 'phosphagen'. These compounds and the enzymes that catalyse their formation and use are present in cells with important and rapidly fluctuating energy requirements.
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