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Cytosolic Forms (cytosolic + form)
Selected AbstractsMembrane-bound and cytosolic forms of heterotrimeric G proteins in young and adult rat myocardium: Influence of neonatal hypo- and hyperthyroidismJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001Jiri Novotny Abstract Membrane and cytosolic fractions prepared from ventricular myocardium of young (21-day-old) hypo- or hyperthyroid rats and adult (84-day-old) previously hypo- or hyperthyroid rats were analyzed by immunoblotting with specific anti-G-protein antibodies for the relative content of Gs,, Gi,/Go,, Gq,/G11,, and G,. All tested G protein subunits were present not only in myocardial membranes but were at least partially distributed in the cytosol, except for Go,2, and G11,. Cytosolic forms of the individual G proteins represented about 5,60% of total cellular amounts of these proteins. The long (Gs,-L) isoform of Gs, prevailed over the short (Gs,-S) isoform in both crude myocardial membranes and cytosol. The Gs,-L/Gs,-S ratio in membranes as well as in cytosol increased during maturation due to a substantial increase in Gs,-L. Interestingly, whereas the amount of membrane-bound Gi,/Go, and Gq,/G11, proteins tend to lower during postnatal development, cytosolic forms of these G proteins mostly rise. Neonatal hypothyroidism reduced the amount of myocardial Gs, and increased that of Gi,/Go, proteins. By contrast, neonatal hyperthyroidism increased expression of Gs, and decreased that of Gi, and G11, in young myocardium. Changes in G protein content induced by neonatal hypo- and hyperthyroidism in young rat myocardium were restored in adulthood. Alterations in the membrane-cytosol balance of G protein subunits associated with maturation or induced by altered thyroid status indicate physiological importance of cytosolic forms of these proteins in the rat myocardium. J. Cell. Biochem. 82: 215,224, 2001. © 2001 Wiley-Liss, Inc. [source] An , -amylase (At4g25000) in Arabidopsis leaves is secreted and induced by biotic and abiotic stressPLANT CELL & ENVIRONMENT, Issue 4 2007ELIZABETH A. DOYLE ABSTRACT Leaves are reported to contain a secreted , -amylase that accumulates during senescence or after biotic or abiotic stress; however, a gene encoding this enzyme has not been described. Because a secreted amylase is isolated from plastidic starch, the function of this enzyme is difficult to predict, but circumstantial evidence suggests that it may degrade starch after cell death. The Arabidopsis thaliana genome contains three , -amylase genes, one of which, AMY1 (At4g25000), has a putative signal sequence suggesting that the protein may be secreted. Two independent T-DNA insertion mutants in AMY1 lacked an amylase band on starch zymograms, which was previously named ,A1'. Washed leaf protoplasts contained reduced A1 activity suggesting that the enzyme is secreted. Native AMY1, fused to a weakly fluorescent form of GFP, was sensitive to proteinase K infiltrated into leaf apoplastic spaces, while a cytosolic form of GFP was unaffected until cell breakage, confirming that the AMY1 protein is secreted. Amylase A1 was transcriptionally induced in senescing leaves and in leaves exposed to heat stress, treated with abscisic acid or infected with Pseudomonas syringae pv. tomato expressing avrRpm1. The A1 amylase was also extremely heat resistant and its expression was up-regulated in cpr5-2, an activated defence response mutant. [source] Membrane-bound and cytosolic forms of heterotrimeric G proteins in young and adult rat myocardium: Influence of neonatal hypo- and hyperthyroidismJOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2001Jiri Novotny Abstract Membrane and cytosolic fractions prepared from ventricular myocardium of young (21-day-old) hypo- or hyperthyroid rats and adult (84-day-old) previously hypo- or hyperthyroid rats were analyzed by immunoblotting with specific anti-G-protein antibodies for the relative content of Gs,, Gi,/Go,, Gq,/G11,, and G,. All tested G protein subunits were present not only in myocardial membranes but were at least partially distributed in the cytosol, except for Go,2, and G11,. Cytosolic forms of the individual G proteins represented about 5,60% of total cellular amounts of these proteins. The long (Gs,-L) isoform of Gs, prevailed over the short (Gs,-S) isoform in both crude myocardial membranes and cytosol. The Gs,-L/Gs,-S ratio in membranes as well as in cytosol increased during maturation due to a substantial increase in Gs,-L. Interestingly, whereas the amount of membrane-bound Gi,/Go, and Gq,/G11, proteins tend to lower during postnatal development, cytosolic forms of these G proteins mostly rise. Neonatal hypothyroidism reduced the amount of myocardial Gs, and increased that of Gi,/Go, proteins. By contrast, neonatal hyperthyroidism increased expression of Gs, and decreased that of Gi, and G11, in young myocardium. Changes in G protein content induced by neonatal hypo- and hyperthyroidism in young rat myocardium were restored in adulthood. Alterations in the membrane-cytosol balance of G protein subunits associated with maturation or induced by altered thyroid status indicate physiological importance of cytosolic forms of these proteins in the rat myocardium. J. Cell. Biochem. 82: 215,224, 2001. © 2001 Wiley-Liss, Inc. [source] Cyclic ADP-ribose as a potential second messenger for neuronal Ca2+ signalingJOURNAL OF NEUROCHEMISTRY, Issue 2 2001Haruhiro Higashida Cyclic ADP-ribose (cADPR), a known endogenous modulator of ryanodine receptor Ca2+ releasing channels, is found in the nervous system. Injection of cADPR into neuronal cells primarily induces a transient elevation of intracellular Ca2+ concentration ([Ca2+]i), and/or secondarily potentiates [Ca2+]i increases that are the result of depolarization-induced Ca2+ influx. Acetylcholine release from cholinergic neurons is facilitated by cADPR. cADPR modifies K+ currents or elicits Ca2+ -dependent inward currents. cADPR is synthesized by both membrane-bound and cytosolic forms of ADP-ribosyl cyclase in neuronal cells. cADPR hydrolase activity is weak in the membrane fraction, but high in the cytoplasm. Cytosolic ADP-ribosyl cyclase activity is upregulated by nitric oxide/cyclic GMP-dependent phosphorylation. Stimulation of muscarinic and ,-adrenergic receptors activates membrane-bound ADP-ribosyl cyclase via G proteins within membranes of neuronal tumor cells and cortical astrocytes. These findings strongly suggest that cADPR is a second messenger in Ca2+ signaling in the nervous system, although many intriguing issues remain to be addressed before this identity is confirmed. [source] | ||||||||||