Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.3.3.1 (citrate synthase)
 4,488 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Partially or completely unfolded polypeptides are highly prone to aggregation due to nonspecific interactions between their exposed hydrophobic surfaces. Extracellular proteins are continuously subjected to stresses conditions, but the existence of extracellular chaperones remains largely unexplored. The results presented here demonstrate that one of the most abundant extracellular proteins, fibrinogen has chaperone-like activity. Fibrinogen can specifically bind to nonnative form of citrate synthase and inhibit its thermal aggregation and inactivation in an ATP-independent manner. Interestingly, fibrinogen maintains thermal-denatured luciferase in a refolding competent state allowing luciferase to be refolded in cooperation with rabbit reticulocyte lysate. Fibrinogen also inhibits fibril formation of yeast prion protein Sup35 (NM). Furthermore, fibrinogen rescues thermal-induced protein aggregation in the plasma of fibrinogen-deficient mice. Our studies demonstrate the chaperone-like activity of fibrinogen, which not only provides new insights into the extracellular chaperone protein system, but also suggests potential diagnostic and therapeutic approaches to fibrinogen-related pathological conditions.
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PMID:Fibrinogen has chaperone-like activity. 1905 6

Human fibrinogen is an important coagulation factor as well as an acute phase protein in the circulatory system. Fibrinogen-420 is distinguished from the conventional alpha chain of fibrinogen-340 by the presence of an additional 236-residue carboxyl terminus globular domain (alpha(E)C). The alpha(E)C domain of human fibrinogen-420 is a stable and early proteolytic cleavage product in the circulation. A genuine physiological function for alpha(E)C has not yet been established. Our study aims to characterize the novel chaperone-like activity of alpha(E)C. alpha(E)C efficiently protects a series of model proteins from thermally induced aggregation. Furthermore, alpha(E)C specifically recognizes the partially denatured form instead of the native form of citrate synthase (CS) and potentially protects it from thermally induced inactivation. The protective effect may result from formation of soluble complexes between alpha(E)C and partially denatured CS as tested by size exclusion column and electron microscope. In addition, alpha(E)C can keep the partially denatured luciferase in a folding competent state and help it refold in cooperation with rabbit reticulocyte lysate (RRL). Furthermore, alpha(E)C can also form complexes with thermally stressed plasma proteins. Our findings reveal the novel function of alpha(E)C as a chaperone-like protein, which not only provides new insights into the extracellular chaperone system but also has implications on the physiological and pathological relevance of fibrinogen.
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PMID:Alpha(E)C, the C-terminal extension of fibrinogen, has chaperone-like activity. 1928 87