scholarly journals Reversal of the Ca2+ pump of blood platelets

1995 ◽  
Vol 306 (1) ◽  
pp. 35-38 ◽  
Author(s):  
J C Benech ◽  
H Wolosker ◽  
L de Meis
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Blood Platelets ◽  
Specific Inhibitor ◽  
Amino Acid Sequences ◽  
Transport Systems ◽  
Muscle Enzyme ◽  
Transport Atpase

In this study, the endoplasmic Ca2+ transport ATPase of blood platelets was compared with the Ca2+ ATPase of sarcoplasmic reticulum skeletal muscle. Similar to the muscle enzyme, the Ca2+ ATPase from platelets was found to catalyse an ATP<-->P(i) exchange both in the presence and in the absence of a transmembrane Ca2+ gradient. When platelet vesicles are loaded with Ca2+ and diluted in medium containing ADP, P(i) and EGTA, the ATPase catalyses Ca2+ efflux coupled to synthesis of ATP. The stoichiometry between Ca2+ ion released and ATP synthesized by platelet Ca2+ ATPase is 1, while that of skeletal muscle is 2. Thapsigargin, a specific inhibitor of sarcoplasmic/endoplasmic reticulum Ca2+ ATPases, inhibited both the Ca(2+)-dependent ATPase activity and the reversal of the platelet Ca2+ pump. The possibility is discussed that the differences observed between the two transport systems is related to the distinct amino acid sequences of the enzymes.

scholarly journals Ethanol has different effects on Ca2+-transport ATPases of muscle, brain and blood platelets

1995 ◽  
Vol 312 (3) ◽  
pp. 733-737 ◽  
Author(s):  
F Mitidieri ◽  
L de Meis
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Atpase Activity ◽  
Blood Platelets ◽  
Activity Increase ◽  
Low Concentrations ◽  
Biphasic Effect ◽  
Transport Atpases

The effects of ethanol on different sarco/endoplasmic reticulum Ca(2+)-transport ATPases (SERCAs) were studied. In sarcoplasmic reticulum vesicles, ethanol concentrations varying from 5 to 20% promoted a progressive inhibition of Ca2+ uptake, enhancement of Ca2+ efflux, activation of the ATPase activity, increase of the enzyme phosphorylation by ATP and inhibition of enzyme phosphorylation by P1. The effects of ethanol on Ca2+ uptake and Ca2+ efflux were antagonized by Mg2+, P(i) and spermine. The increased efflux promoted by ethanol was antagonized by Ca2+ and thapsigargin. In brain and platelet vesicles a biphasic effect of ethanol was observed, so that activation occurred at low concentrations (5-10%) and inhibition at higher concentrations. The activation was not observed with the use of n-propanol and n-butanol. Different from the situation in sarcoplasmic reticulum, the decrease of the Ca2+ uptake in brain and platelet vesicles was associated with an inhibition of the ATPase activity. Mg2+ and P(i) antagonized the enhancement of Ca2+ efflux and the inhibition of Ca2+ uptake promoted by ethanol. However, thapsigargin and Ca2+ did not arrest the Ca2+ efflux promoted by ethanol in brain and platelet preparations. These results suggest that, in sarcoplasmic reticulum vesicles, ethanol uncouples the pump, promoting its activity as a Ca2+ channel. The SERCA isoform found in skeletal muscle has different properties from the isoforms found in brain and blood platelets.

Peripheral membrane proteins of sarcoplasmic and endoplasmic reticulum. Comparison of carboxyl-terminal amino acid sequences

1989 ◽  
Vol 67 (10) ◽  
pp. 696-702 ◽  
Author(s):  
Larry Fliegel ◽  
Kimberly Burns ◽  
Ken Wlasichuk ◽  
Marek Michalak
Keyword(s):  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Membrane Proteins ◽  
Binding Protein ◽  
Amino Acid Sequences ◽  
Endoplasmic Reticulum Membrane ◽  
Peripheral Membrane Proteins ◽  
Carboxyl Terminal ◽  
Retention Signal

Peripheral endoplasmic reticulum membrane proteins residing in the lumen of the endoplasmic reticulum occupy the same space as other secreted proteins. The presence of a four amino acid salvage or retention signal (KDEL-COOH = Lys-Asp-Glu-Leu-COOH) at the carboxyl-terminal end of peripheral membrane proteins has been shown to represent a signal or an essential part of a signal for their retention within the endoplasmic reticulum membrane. In heart and skeletal muscle, a number of sarcoplasmic reticulum proteins have recently been identified which are peripheral membrane proteins. The high-affinity calcium-binding protein (55 kilodaltons (kDa)) appears to conform to the above described mechanisms and contains the KDEL carboxyl-terminal tetrapeptide. Thyroid hormone binding protein is present in the sarcoplasmic reticulum, in addition to its endoplasmic reticulum location, and has a modified but related tetrapeptide sequence (RDEL = Arg-Asp-Glu-Leu), which also probably functions as the retention signal. Calsequestrin and a 53-kDa glycoprotein, two other peripheral membrane proteins residing in the lumen of the sarcoplasmic reticulum, do not contain the KDEL retention signal. The sarcoplasmic reticulum may have developed a unique retention mechanism(s) for these muscle-specific proteins.Key words: sarcoplasmic reticulum, endoplasmic reticulum, amino acid sequences, peripheral membrane proteins, KDEL retention sequence.

scholarly journals Smooth muscle expresses a cardiac/slow muscle isoform of the Ca2+-transport ATPase in its endoplasmic reticulum

1989 ◽  
Vol 257 (1) ◽  
pp. 117-123 ◽  
Author(s):  
F Wuytack ◽  
Y Kanmura ◽  
J A Eggermont ◽  
L Raeymaekers ◽  
J Verbist ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Cardiac Muscle ◽  
Muscle Enzymes ◽  
Transport Atpase ◽  
Slow Twitch ◽  
Transport Atpases ◽  
Fast Twitch

Smooth muscle expresses in its endoplasmic reticulum an isoform of the Ca2+-transport ATPase that is very similar to or identical with that of the cardiac-muscle/slow-twitch skeletal-muscle form. However, this enzyme differs from that found in fast-twitch skeletal muscle. This conclusion is based on two independent sets of observations, namely immunological observations and phosphorylation experiments. Immunoblot experiments show that two different antibody preparations against the Ca2+-transport ATPase of cardiac-muscle sarcoplasmic reticulum also recognize the endoplasmic-reticulum/sarcoplasmic-reticulum enzyme of the smooth muscle and the slow-twitch skeletal muscle whereas they bind very weakly or not at all to the sarcoplasmic-reticulum Ca2+-transport ATPase of the fast-twitch skeletal muscle. Conversely antibodies directed against the fast-twitch skeletal-muscle isoform of the sarcoplasmic-reticulum Ca2+-transport ATPase do not bind to the cardiac-muscle, smooth-muscle or slow-twitch skeletal-muscle enzymes. The phosphorylated tryptic fragments A and A1 of the sarcoplasmic-reticulum Ca2+-transport ATPases have the same apparent Mr values in cardiac muscle, slow-twitch skeletal muscle and smooth muscle, whereas the corresponding fragments in fast-twitch skeletal muscle have lower apparent Mr values. This analytical procedure is a new and easy technique for discrimination between the isoforms of endoplasmic-reticulum/sarcoplasmic-reticulum Ca2+-transport ATPases.

scholarly journals Evidence for the presence in smooth muscle of two types of Ca2+-transport ATPase

1984 ◽  
Vol 224 (2) ◽  
pp. 445-451 ◽  
Author(s):  
F Wuytack ◽  
L Raeymaekers ◽  
J Verbist ◽  
H De Smedt ◽  
R Casteels
Keyword(s):  
Skeletal Muscle ◽  
Endoplasmic Reticulum ◽  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Acid Medium ◽  
Erythrocyte Membrane ◽  
Proteolytic Degradation ◽  
Transport Atpase ◽  
Degradation Pattern ◽  
Transport Atpases

Membrane fractions prepared from smooth muscle of the pig stomach (antral part) contain two Ca2+-dependent phosphoprotein intermediates belonging to different Ca2+-transport ATPases. These alkali-labile phosphoproteins can be separated by electrophoresis in acid medium. The 130 kDa phosphoprotein resembles a corresponding protein in the erythrocyte membrane, whereas the 100 kDa protein resembles that of the Ca2+-transport ATPase in sarcoplasmic reticulum from skeletal muscle. These resemblances are expressed in terms of Mr, reaction to La3+ and in a similar proteolytic degradation pattern. The presence of the calmodulin-stimulated ATPase in mixed membranes from smooth muscle is confirmed by its binding of calmodulin and antibodies against erythrocyte Ca2+-transport ATPase, whereas such binding does not occur with proteins present in the presumed endoplasmic reticulum from smooth muscle.

scholarly journals Different Responses of Cytoplasmic and Endoplasmic Reticulum Hsp90 Genes from Eogystia hippophaecola (Lepidoptera: Cossidae) to Cold Stress

Forests ◽  
2019 ◽  
Vol 10 (11) ◽  
pp. 1039
Author(s):  
Qianqian Wang ◽  
Jing Tao ◽  
Yurong Li ◽  
Yabei Xu ◽  
Xinhai Liu ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Amino Acid ◽  
Low Temperature ◽  
Cold Stress ◽  
Cold Tolerance ◽  
Response Times ◽  
Expression Patterns ◽  
Amino Acid Sequences ◽  
Sea Buckthorn ◽  
Open Reading Frames

Eogystia hippophaecola Hua, Chou, Fang et Chen (Lepidoptera: Cossidae) is an important borer pest of the sea buckthorn forest (Hippophae rhamnoides L.) in China. Its larvae, which are highly cold tolerant, mainly overwinter in sea buckthorn roots. Heat shock proteins (Hsps) are important molecular chaperones that have been linked to cold tolerance in insects. In this study, we cloned the open reading frames (ORFs) of two Hsp90 genes from E. hippophaecola, EhHsp90-1 and EhHsp90-2, and analyzed their expression under cold stress by qRT-PCR. EhHsp90-1 and EhHsp90-2 are 2154 and 2346 bp in length, respectively, encoding 717 and 781 amino acids. The deduced amino acid sequences contain the conserved signature sequences of the Hsp90 family and the C-terminus characteristic sequence of cytoplasmic or endoplasmic reticulum Hsp90 protein. Phylogenetic analysis revealed the amino acid sequences of EhHsp90-1 and EhHsp90-2 were very similar to the corresponding proteins from Lepidoptera. Under various low-temperature treatments lasting 2 h, EhHsp90-1 and EhHsp90-2 exhibited similar expression patterns, increasing first and then decreasing. At −5 °C, EhHsp90-1 was significantly up-regulated after 12 h, whereas EhHsp90-2 was up-regulated after just 1 h and reached its highest level at 2 h; however, the overall degree of upregulation was greater for EhHsp90-1. Subsequently, the expression level of EhHsp90-2 fluctuated with time. Our results suggest that the two Hsp90s play important roles in E. hippophaecola larvae response to cold stress, but that their response times and the magnitudes of their responses to low-temperature stress differed significantly, providing a theoretical basis for further studying the molecular mechanism of cold tolerance in E. hippophaecola larvae.

Myocardial amino acid transport by canine sarcolemma vesicles

1987 ◽  
Vol 252 (6) ◽  
pp. H1070-H1076
Author(s):  
L. H. Young ◽  
B. L. Zaret ◽  
E. J. Barrett
Keyword(s):  
Amino Acid ◽  
Sarcoplasmic Reticulum ◽  
Membrane Vesicles ◽  
Amino Acid Uptake ◽  
Ventricular Myocardium ◽  
Transport Systems ◽  
Acid Uptake ◽  
Leucine Uptake ◽  
Alanine Transport ◽  
Canine Ventricular Myocardium

The transport of L-alanine and L-leucine into membrane vesicles isolated from mature canine ventricular myocardium was studied. Transport was assessed in purified sarcolemma and in vesicles differentially enriched either for sarcolemma or sarcoplasmic reticulum to further localize these transport systems. An imposed inward gradient of a NaNO3 stimulated uptake of L-alanine but not L-leucine by these vesicles. Amino acid uptake by these vesicles occurred into an osmotically active space. The stimulatory effect of Na+ on alanine transport was most striking in the purified sarcolemma vesicles, where Na+-stimulated alanine flux was 45 +/- 14 pmol X mg-1 X min-1. Furthermore, Na+-dependent alanine transport activity appeared to copurify with Na+-K+-ATPase activity, which served as a marker for sarcolemma membrane when these activities were compared in the three different membrane preparations. Leucine transport by sarcolemma was not altered by an imposed Na+ gradient. However, leucine uptake was a saturable function of extravesicular leucine and was inhibited by valine. In contrast, in sarcoplasmic reticulum membrane vesicles leucine uptake increased proportionately with increasing media leucine and was unaffected by valine. Our results demonstrate the feasibility of directly studying the transport of naturally occurring amino acids in membrane vesicles from mammalian heart, and the presence of Na+-dependent alanine transport system and a Na+-independent leucine transporter in the sarcolemma but not in sarcoplasmic reticulum of canine ventricular myocardium.

Rapid anisotropic motion of the Ca2+-transport ATPase of the rabbit skeletal muscle sarcoplasmic reticulum

1977 ◽  
Vol 55 (6) ◽  
pp. 587-596 ◽  
Author(s):  
Barbara A. Manuck ◽  
Brian D. Sykes
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Relaxation Times ◽  
Rotational Correlation Time ◽  
Rabbit Skeletal Muscle ◽  
Nuclear Spin Relaxation ◽  
Anisotropic Model ◽  
Transport Atpase ◽  
Anisotropic Motion ◽  
Membrane Bound

1H nuclear magnetic resonance techniques were used to study the binding of uridine 5′-triphosphate to the Ca2+-transport ATPase (EC 3.6.1.3) of sarcoplasmic reticulum vesicles from rabbit skeletal muscle. The nuclear spin relaxation times determined for the bound nucleotide are used to characterize the rotational motion of the ATPase to which the nucleotide is bound. The results, assuming an anisotropic model for the motion of the ATPase in the membrane, place a low upper limit on the rotational correlation time of the ATPase. This indicates that the motion of the ATPase in the membrane is quite rapid when compared, for example, with the motion found for other membrane-bound proteins such as rhodopsin.

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