scholarly journals Seminalplasmin. An endogenous calmodulin antagonist

1985 ◽  
Vol 230 (1) ◽  
pp. 277-280 ◽  
Author(s):  
K Gietzen ◽  
H J Galla
Keyword(s):  
Basic Protein ◽  
Electrostatic Forces ◽  
High Potency ◽  
Calmodulin Antagonist ◽  
Basal Activity ◽  
Bull Semen ◽  
Stimulation Of

Seminalplasmin, a strongly basic protein isolated from bull semen, was found to antagonize with high potency and extraordinary specificity the function of calmodulin. Calmodulin antagonism is the result of an interaction between the two proteins, which is mainly determined by electrostatic forces. The stimulation of Ca2+-transporting ATPase and phosphodiesterase by calmodulin was half-maximally inhibited at approx. 0.1 microM-seminalplasmin. However, the basal activity of calmodulin-dependent enzymes was not significantly altered by seminalplasmin over the concentration range investigated.

Stimulation of Strontium Accumulation in Linoleate-Enriched Saccharomyces cerevisiae Is a Result of Reduced Sr2+ Efflux

1999 ◽  
Vol 65 (3) ◽  
pp. 1191-1197 ◽  
Author(s):  
Simon V. Avery ◽  
Shareeka L. Smith ◽  
A. Mohamad Ghazi ◽  
Michael J. Hoptroff
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fatty Acids ◽  
Plasma Membrane ◽  
Fatty Acid ◽  
Atpase Inhibitor ◽  
Calmodulin Antagonist ◽  
Wide Range ◽  
Fatty Acid Supplement ◽  
Accumulation Ability ◽  
Stimulation Of

ABSTRACT The influence of modified plasma membrane fatty acid composition on cellular strontium accumulation in Saccharomyces cerevisiaewas investigated. Growth of S. cerevisiae in the presence of 1 mM linoleate (18:2) (which results in 18:2 incorporation to ∼70% of total cellular and plasma membrane fatty acids, with no effect on growth rate) yielded cells that accumulated Sr2+ intracellularly at approximately twice the rate ofS. cerevisiae grown without a fatty acid supplement. This effect was evident over a wide range of external Sr2+concentrations (25 μM to 5 mM) and increased with the extent of cellular 18:2 incorporation. Stimulation of Sr2+accumulation was not evident following enrichment of S. cerevisiae with either palmitoleate (16:1), linolenate (18:3) (n-3 and n-6 isomers), or eicosadienoate (20:2) (n-6 and n-9 isomers). Competition experiments revealed that Ca2+- and Mg2+-induced inhibition of Sr2+ accumulation did not differ between unsupplemented and 18:2-supplemented cells. Treatment with trifluoperazine (TFP) (which can act as a calmodulin antagonist and Ca2+-ATPase inhibitor), at a low concentration that precluded nonspecific K+ efflux, increased intracellular Sr2+ accumulation by approximately 3.6- and 1.4-fold in unsupplemented and 18:2-supplemented cells, respectively. Thus, TFP abolished the enhanced Sr2+ accumulation ability of 18:2-supplemented cells. Moreover, the rate of Sr2+release from Sr2+-loaded fatty acid-unsupplemented cells was found to be at least twice as great as that from Sr2+-loaded 18:2-enriched cells. The influence of enrichment with other fatty acids on Sr2+ efflux was variable. The results reveal an enhanced Sr2+ accumulation ability of S. cerevisiae following 18:2-enrichment, which is attributed to diminished Sr2+ efflux activity in these cells.

scholarly journals Calmidazolium and arachidonate activate a calcium entry pathway that is distinct from store-operated calcium influx in HeLa cells

2004 ◽  
Vol 381 (3) ◽  
pp. 929-939 ◽  
Author(s):  
Claire M. PEPPIATT ◽  
Anthony M. HOLMES ◽  
Jeong T. SEO ◽  
Martin D. BOOTMAN ◽  
Tony J. COLLINS ◽  
...  
Keyword(s):  
Hela Cells ◽  
Calcium Influx ◽  
Differential Sensitivity ◽  
Excitable Cells ◽  
Hormonal Stimulation ◽  
Calmodulin Antagonist ◽  
Alternative Pathways ◽  
Entry Pathway ◽  
Store Depletion ◽  
Stimulation Of

Agonists that deplete intracellular Ca2+ stores also activate Ca2+ entry, although the mechanism by which store release and Ca2+ influx are linked is unclear. A potential mechanism involves ‘store-operated channels’ that respond to depletion of the intracellular Ca2+ pool. Although SOCE (store-operated Ca2+ entry) has been considered to be the principal route for Ca2+ entry during hormonal stimulation of non-electrically excitable cells, recent evidence has suggested that alternative pathways activated by metabolites such as arachidonic acid are responsible for physiological Ca2+ influx. It is not clear whether such messenger-activated pathways exist in all cells, whether they are truly distinct from SOCE and which metabolites are involved. In the present study, we demonstrate that HeLa cells express two pharmacologically and mechanistically distinct Ca2+ entry pathways. One is the ubiquitous SOCE route and the other is an arachidonate-sensitive non-SOCE. We show that both these Ca2+ entry pathways can provide long-lasting Ca2+ elevations, but that the channels are not the same, based on their differential sensitivity to 2-aminoethoxydiphenyl borate, LOE-908 {(R,S)-(3,4-dihydro-6,7-dimethoxy-isochinolin-1-yl)-2-phenyl-N,N-di[2-(2,3,4-trimethoxyphenyl)ethyl]acetamid mesylate} and gadolinium. In addition, non-SOCE and not SOCE was permeable to strontium. Furthermore, unlike SOCE, the non-SOCE pathway did not require store depletion and was not sensitive to displacement of the endoplasmic reticulum from the plasma membrane using jasplakinolide or ionomycin pretreatment. These pathways did not conduct Ca2+ simultaneously due to the dominant effect of arachidonate, which rapidly curtails SOCE and promotes Ca2+ influx via non-SOCE. Although non-SOCE could be activated by exogenous application of arachidonate, the most robust method for stimulation of this pathway was application of the widely used calmodulin antagonist calmidazolium, due to its ability to activate phospholipase A2.

scholarly journals Orthovanadate Stimulates Cyclic Guanosine Monophosphate-Inhibited Cyclic Adenosine Monophosphate Phosphodiesterase Activity in Isolated Rat Fat Pads through Activation of Particulate Myelin Basic Protein Kinase by Protein Tyrosine Kinase

Endocrinology ◽  
1997 ◽  
Vol 138 (7) ◽  
pp. 2784-2789 ◽  
Author(s):  
Hiroshi Ueki ◽  
Shuichi Mitsugi ◽  
Yoshihito Kawashima ◽  
Toshio Motoyashiki ◽  
Tetsuo Morita
Keyword(s):  
Protein Kinase ◽  
Tyrosine Kinase ◽  
Myelin Basic Protein ◽  
Protein Tyrosine Kinase ◽  
Basic Protein ◽  
Major Protein ◽  
Dependent Manner ◽  
Protein Tyrosine ◽  
Fat Pads ◽  
Stimulation Of

Abstract Involvement of protein kinases in the stimulation of cGMP-inhibited cAMP phosphodiesterase (PDE) activity by orthovanadate (vanadate) was studied. When the fat pads were incubated with 2 mm vanadate or 10 nm insulin, the stimulation of myelin basic protein kinase (MBPK) activity in the particulate by vanadate reached a maximum at 60 min. In contrast, insulin showed a transient increase at 20 min. A 60-min incubation of the fat pads with vanadate stimulated all activities of protein tyrosine kinase (PTK), MBPK, and PDE in the particulate, in a similar dose-dependent manner. Amiloride, a PTK inhibitor, inhibited the stimulations of three enzymes by vanadate in a similar concentration range. Enzyme fractions, which were separated from the solubilized particulate, were subjected to the immunoblot analysis. A fraction of MBPK was identified to contain a major protein of mol wt (44K) and a minor one (42K), both of which are immunoreactive with a mitogen-activated protein kinase (MAPK) antibody. The partially purified PDE activity was stimulated by the addition of the partially purified MBPK. The further stimulation was observed with the PTK-activated MBPK. These results suggest that vanadate stimulates in part the PDE activity through the activation of the particulate MBPK, probably MAPKs, by PTK sensitive to vanadate.

GABA-Mediated Trophic Effect on Oligodendrocytes Requires Na-K-2Cl Cotransport Activity

2003 ◽  
Vol 90 (2) ◽  
pp. 1257-1265 ◽  
Author(s):  
Hao Wang ◽  
Yiping Yan ◽  
Douglas B. Kintner ◽  
Christian Lytle ◽  
Dandan Sun
Keyword(s):  
Spinal Cord ◽  
Growth Factors ◽  
Basic Protein ◽  
Rat Spinal Cord ◽  
Animal Cells ◽  
Cell Shrinkage ◽  
Trophic Effect ◽  
Intracellular Ca ◽  
Electrochemical Equilibrium ◽  
Stimulation Of

The Na-K-2Cl cotransporter isoform1 (NKCC1) is present in many animal cells where it plays prominent roles in regulating cell volume and maintaining intracellular Cl– concentration ([Cl–]i) above electrochemical equilibrium. We show here that NKCC1 is present and active in cultured oligodendrocytes. Expression of NKCC1 in the rat spinal cord increased during development from postnatal day 6 through 21 in parallel with that of myelin basic protein. In cultured oligodendrocytes, 39% of the total K+ (86Rb+) influx represented NKCC1 activity. Activation of GABAA receptors with muscimol produced a reduction in intracellular Cl– content, cell shrinkage, and a stimulation of NKCC1 activity. Muscimol also triggered an increase in intracellular Ca2+, which depended on NKCC1 activity. Survival of oligodendrocytes following withdrawal of growth factors was enhanced by muscimol and this effect also required NKCC1 activity. Our results suggest that NKCC1 functions in oligodendrocytes to maintain [Cl–]i above electrochemical equilibrium and that NKCC1 is required for GABAergic trophic effects.

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