The Ca2+ sensitivity of liver gelactin

1987 ◽  
Vol 65 (6) ◽  
pp. 543-546
Author(s):  
Hélène-Marie Thérien ◽  
Julian Gruda
Keyword(s):  
Calcium Ion ◽  
Actin Polymerization ◽  
Calcium Sensitivity ◽  
Ion Concentration ◽  
Free Calcium ◽  
Low Concentrations ◽  
Low Shear Viscosity ◽  
Calcium Ion Concentration ◽  
Low Shear

The Ca2+ sensitivity of liver gelactin-induced actin gelation was reinvestigated by low-shear viscosity using the falling-ball technique. By this technique, we demonstrate that the gelation of actin by gelactin can be influenced by the presence of calcium ions depending on the concentrations of both proteins, actin and gelactin. At low concentrations of gelactin, the gelation of actin exhibits a bell-shaped dependency on free calcium ion concentration, being stimulated between pCa 8 and 6 and inhibited at pCa below 5.5, while at high gelactin concentrations the calcium sensitivity of actin gelation is apparently abolished. Although the sensitivity observed in the physiological range of calcium concentrations may be of importance in vivo, the sensitivity observed at higher calcium concentrations more probably reflects the state of actin polymerization in different ionic conditions. These results confirm our previous conclusions on the peculiarity of gelactin as an F-actin cross-linker.

Dependence of Cardiac Contractility on Myofibrillar Calcium Sensitivity

Physiology ◽  
1987 ◽  
Vol 2 (5) ◽  
pp. 179-182
Author(s):  
JC Ruegg
Keyword(s):  
Calcium Ion ◽  
Sarcomere Length ◽  
Cardiac Contractility ◽  
Calcium Sensitivity ◽  
Ion Concentration ◽  
Free Calcium ◽  
Wide Range ◽  
Heart Contractility ◽  
Calcium Ion Concentration

In the heart, contractility may be varied over a wide range. It is determined mainly by the myoplasmic free calcium ion concentration. However, alteration of the responsiveness of the myofilaments to calcium may also be important in regulating cardiac contractility, in particular following changes in sarcomere length, or in hypoxia, or after interventions with certain novel cardiotonic drugs.

scholarly journals Fluorescence microscope study of the binding of added C protein to skeletal muscle myofibrils.

1981 ◽  
Vol 90 (1) ◽  
pp. 25-31 ◽  
Author(s):  
C Moos
Keyword(s):  
Skeletal Muscle ◽  
Fluorescence Microscopy ◽  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Myofibrillar Atpase ◽  
C Protein ◽  
Thick Filaments ◽  
Calcium Ion Concentration

The binding of extra C protein to rabbit skeletal muscle myofibrils has been investigated by fluorescence microscopy with fluorescein-labeled C protein or unmodified C protein plus fluorescein-labeled anti-C protein. Added C protein binds strongly to the I bands, which is consistent with its binding to F actin in solution (Moos, C., C. M. Mason, J. M. Besterman, I. M. Feng, and J. H. Dubin. 1978. J. Mol. Biol. 124:571-586). Of particular interest, the binding to the I band is calcium regulated: it requires a free calcium ion concentration comparable to that which activates the myofibrillar ATPase. This increases the likelihood that C protein-actin interaction might be physiologically significant. When I band binding is suppressed, binding in the A band becomes evident. It appears to occur particularly near the M line, and possibly at the edges of the A band as well, suggesting that those parts of the thick filaments that lack C protein in vivo may nevertheless be capable of binding added C protein.

Bile canalicular contraction in the isolated hepatocyte doublet is related to an increase in cytosolic free calcium ion concentration

2008 ◽  
Vol 8 (3) ◽  
pp. 178-183 ◽  
Author(s):  
Sumio Watanabe ◽  
Masahiro Tomono ◽  
Makoto Takeuchi ◽  
Tsuneo Kitamura ◽  
Miyoko Hirose ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Bile Canalicular Contraction ◽  
Calcium Ion Concentration

scholarly journals The gravistimulation-induced very slow Ca2+ increase in Arabidopsis seedlings requires MCA1, a Ca2+-permeable mechanosensitive channel

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Masataka Nakano ◽  
Takuya Furuichi ◽  
Masahiro Sokabe ◽  
Hidetoshi Iida ◽  
Hitoshi Tatsumi
Keyword(s):  
Calcium Ion ◽  
Channel Blocker ◽  
Upright Position ◽  
Ion Concentration ◽  
Early Event ◽  
Free Calcium ◽  
Permeable Channel ◽  
Mechanosensitive Ion Channel ◽  
And Function ◽  
Calcium Ion Concentration

AbstractGravity is a critical environmental factor affecting the morphology and function of plants on Earth. Gravistimulation triggered by changes in the gravity vector induces an increase in the cytoplasmic free calcium ion concentration ([Ca2+]c) as an early process of gravity sensing; however, its role and molecular mechanism are still unclear. When seedlings of Arabidopsis thaliana expressing apoaequorin were rotated from the upright position to the upside-down position, a biphasic [Ca2+]c-increase composed of a fast-transient [Ca2+]c-increase followed by a slow [Ca2+]c-increase was observed. We find here a novel type [Ca2+]c-increase, designated a very slow [Ca2+]c-increase that is observed when the seedlings were rotated back to the upright position from the upside-down position. The very slow [Ca2+]c-increase was strongly attenuated in knockout seedlings defective in MCA1, a mechanosensitive Ca2+-permeable channel (MSCC), and was partially restored in MCA1-complemented seedlings. The mechanosensitive ion channel blocker, gadolinium, blocked the very slow [Ca2+]c-increase. This is the first report suggesting the possible involvement of MCA1 in an early event related to gravity sensing in Arabidopsis seedlings.

Cold-induced cytosolic free calcium ion concentration changes in wheat

2009 ◽  
Vol 166 (17) ◽  
pp. 1955-1960 ◽  
Author(s):  
J. Nagel-Volkmann ◽  
C. Plieth ◽  
D. Becker ◽  
H. Lüthen ◽  
K. Dörffling
Keyword(s):  
Calcium Ion ◽  
Ion Concentration ◽  
Free Calcium ◽  
Cytosolic Free Calcium ◽  
Concentration Changes ◽  
Calcium Ion Concentration

Free calcium ion concentration in the sieve-tube sap of Ricinus communis L. seedlings

Planta ◽  
1998 ◽  
Vol 206 (1) ◽  
pp. 103-107 ◽  
Author(s):  
Moni Brauer ◽  
Wen-Jun Zhong ◽  
Till Jelitto ◽  
Christian Schobert ◽  
Dale Sanders ◽  
...  
Keyword(s):  
Calcium Ion ◽  
Ricinus Communis ◽  
Sieve Tube ◽  
Ion Concentration ◽  
Free Calcium ◽  
Ricinus Communis L ◽  
Calcium Ion Concentration
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