scholarly journals The β-isoform of BCCIP promotes ADP release from the RAD51 presynaptic filament and enhances homologous DNA pairing

2016 ◽  
Vol 45 (2) ◽  
pp. 711-725 ◽  
Author(s):  
Andrew A. Kelso ◽  
Steven D. Goodson ◽  
Leah E. Watts ◽  
LeAnna L. Ledford ◽  
Sarah M. Waldvogel ◽  
...  
Keyword(s):  
Adp Release ◽  
Dna Pairing

Difference of [Ca2+]i Movements in Platelets Stimulated by Thrombin and TRAP: the Involvement of αIIbβ3-Mediated TXA2 Synthesis

1998 ◽  
Vol 79 (06) ◽  
pp. 1184-1190 ◽  
Author(s):  
Yoshiaki Tomiyama ◽  
Shigenori Honda ◽  
Kayoko Senzaki ◽  
Akito Tanaka ◽  
Mitsuru Okubo ◽  
...  
Keyword(s):  
Platelet Aggregation ◽  
Fibrinogen Binding ◽  
Adp Release ◽  
The Difference ◽  
Txa2 Receptor Antagonist ◽  
High Level ◽  
Inhibition Studies ◽  
Peak Increase ◽  
Second Peak ◽  
Assay Conditions

SummaryThis study investigated the difference of [Ca2+]i movement in platelets in response to thrombin and TRAP. The involvement of αIIbβ3 in this signaling was also studied. Stimulation of platelets with thrombin at 0.03 U/ml caused platelet aggregation and a two-peak increase in [Ca2+]i. The second peak of [Ca2+]i, but not the first peak was abolished by the inhibition of platelet aggregation with αIIbβ3 antagonists or by scavenging endogenous ADP with apyrase. A cyclooxygenase inhibitor, aspirin, and a TXA2 receptor antagonist, BM13505, also abolished the second peak of [Ca2+]i but not the first peak, although these regents did not inhibit aggregation. Under the same assay conditions, measurement of TXB2 demonstrated that αIIbβ3 antagonists and aspirin almost completely inhibited the production of TXB2. In contrast to thrombin-stimulation, TRAP caused only a single peak of [Ca2+]i even in the presence of platelet aggregation, and a high level of [Ca2+]i increase was needed for the induction of platelet aggregation. The inhibition of aggregation with αIIbβ3 antagonists had no effect on [Ca2+]i change and TXB2 production induced by TRAP. Inhibition studies using anti-GPIb antibodies suggested that GPIb may be involved in the thrombin response, but not in the TRAP. Our findings suggest that low dose thrombin causes a different [Ca2+]i response and TXA2 producing signal from TRAP. Endogenous ADP release and fibrinogen binding to αIIbβ3 are responsible for the synthesis of TXA2 which results in the induction of the second peak of [Ca2+]i in low thrombin- but not TRAP-stimulated platelets.

Inhibition by Phenol and Phenolic Acids of Platelet Release Reaction

1973 ◽  
Vol 30 (02) ◽  
pp. 334-338 ◽  
Author(s):  
Felisa C. Molinas
Keyword(s):  
Renal Failure ◽  
Phenolic Compounds ◽  
Phenolic Acids ◽  
Platelet Function ◽  
Deleterious Effect ◽  
Release Reaction ◽  
Contributory Factors ◽  
Adp Release ◽  
Platelet Release

SummaryIt has been postulated that the high phenol and phenolic acids plasmatic levels found in patients with chronic renal failure are contributory factors in the abnormal platelet function described in these patients. This hypothesis was corroborated by “in vitro” studies showing the deleterious effect of these compounds on certain platelet function after pre-incubation of PRP with phenol and phenolic compounds. The present studies were conducted to determine the influence of phenolic compounds on platelet release reaction. It was found that phenol inhibited from 62.5 to 100% the effect of the aggregating agents thrombin, adrenaline and ADP on platelet 5-HT-14C release. The phenolic acids p-, m-, and o-HPAA inhibited from 36.35 to 94.8% adrenaline and ADP-induced platelet 5-HT-14C release. Adrenaline-induced platelet ADP release was inhibited from 27.45 to 38.10% by the phenolic compounds. These findings confirm the hypothesis that phenolic compounds interfere with platelet function through the inhibition of the release reaction.

scholarly journals Unraveling a Force-Generating Allosteric Pathway of Actomyosin Communication Associated with ADP and Pi Release

2020 ◽  
Vol 22 (1) ◽  
pp. 104
Author(s):  
Peter Franz ◽  
Wiebke Ewert ◽  
Matthias Preller ◽  
Georgios Tsiavaliaris
Keyword(s):  
Structural Changes ◽  
Atp Hydrolysis ◽  
Power Stroke ◽  
Duty Ratio ◽  
Prolonged Duration ◽  
Adp Release ◽  
Strong Transition ◽  
Cleft Closure ◽  
Kinetic Investigations ◽  
Allosteric Pathway

The actomyosin system generates mechanical work with the execution of the power stroke, an ATP-driven, two-step rotational swing of the myosin-neck that occurs post ATP hydrolysis during the transition from weakly to strongly actin-bound myosin states concomitant with Pi release and prior to ADP dissociation. The activating role of actin on product release and force generation is well documented; however, the communication paths associated with weak-to-strong transitions are poorly characterized. With the aid of mutant analyses based on kinetic investigations and simulations, we identified the W-helix as an important hub coupling the structural changes of switch elements during ATP hydrolysis to temporally controlled interactions with actin that are passed to the central transducer and converter. Disturbing the W-helix/transducer pathway increased actin-activated ATP turnover and reduced motor performance as a consequence of prolonged duration of the strongly actin-attached states. Actin-triggered Pi release was accelerated, while ADP release considerably decelerated, both limiting maximum ATPase, thus transforming myosin-2 into a high-duty-ratio motor. This kinetic signature of the mutant allowed us to define the fractional occupancies of intermediate states during the ATPase cycle providing evidence that myosin populates a cleft-closure state of strong actin interaction during the weak-to-strong transition with bound hydrolysis products before accomplishing the power stroke.

Deafness mutation in the MYO3A motor domain impairs actin protrusion elongation mechanism

2021 ◽  
Author(s):  
Laura K. Gunther ◽  
Joseph A Cirilo ◽  
Rohini Desetty ◽  
Christopher M. Yengo
Keyword(s):  
Atp Hydrolysis ◽  
Kinetic Mechanism ◽  
Duty Ratio ◽  
Slight Reduction ◽  
Average Intensity ◽  
Class Iii ◽  
Length Regulation ◽  
Adp Release ◽  
Actin Protrusions

Class III myosins are actin-based motors proposed to transport cargo to the distal tips of stereocilia in the inner ear hairs cells and/or to participate in stereocilia length regulation, which is especially important during development. Mutations in the MYO3A gene are associated with delayed onset deafness. A previous study demonstrated that L697W, a dominant deafness mutation, disrupts MYO3A ATPase and motor properties but does not impair its ability to localize to the tips of actin protrusions. In the current study, we characterized the transient kinetic mechanism of the L697W motor ATPase cycle. Our kinetic analysis demonstrates that the mutation slows the ADP release and ATP hydrolysis steps, which results in a slight reduction in the duty ratio and slows detachment kinetics. Fluorescence recovery after photobleaching (FRAP) of filopodia tip localized L697W and WT MYO3A in COS-7 cells revealed that the mutant does not alter turnover or average intensity at the actin protrusion tips. We demonstrate that the mutation slows filopodia extension velocity in COS-7 cells which correlates with its 2-fold slower in vitro actin gliding velocity. Overall, this work allowed us to propose a model for how the motor properties of MYO3A are crucial for facilitating actin protrusion length regulation.

scholarly journals Coiled-coil 1-mediated fastening of the neck and motor domains for kinesin-3 autoinhibition

2018 ◽  
Vol 115 (51) ◽  
pp. E11933-E11942 ◽  
Author(s):  
Jinqi Ren ◽  
Shuang Wang ◽  
Han Chen ◽  
Wenjuan Wang ◽  
Lin Huo ◽  
...  
Keyword(s):  
Coiled Coil ◽  
Underlying Mechanism ◽  
Motor Domain ◽  
Dimer Formation ◽  
Interaction Interface ◽  
Adp Release ◽  
Interdomain Interaction ◽  
Neck Domain ◽  
Neck Coil

In kinesin-3, the coiled-coil 1 (CC1) can sequester the preceding neck coil (NC) for autoinhibition, but the underlying mechanism is poorly understood. Here, we determined the structures of the uninhibited motor domain (MD)-NC dimer and inhibited MD-NC-CC1 monomer of kinesin-3 KIF13B. In the MD-NC-CC1 monomer, CC1 is broken into two short helices that unexpectedly interact with both the NC and the MD. Compared with the MD-NC dimer, the CC1-mediated integration of NC and MD not only blocks the NC dimer formation, but also prevents the neck linker (NL) undocking and the ADP release from the MD. Mutations of the essential residues in the interdomain interaction interface in the MD-NC-CC1 monomer restored the MD activity. Thus, CC1 fastens the neck domain and MD and inhibits both NC and NL. This CC1-mediated lockdown of the entire neck domain may represent a paradigm for kinesin autoinhibition that could be applicable to other kinesin-3 motors.

Microtubules accelerate ADP release by dynein

Biochemistry ◽  
1989 ◽  
Vol 28 (17) ◽  
pp. 7010-7016 ◽  
Author(s):  
Erika L. F. Holzbaur ◽  
Kenneth A. Johnson
Keyword(s):  
Adp Release

scholarly journals Conserved mechanisms of microtubule-stimulated ADP release, ATP binding, and force generation in transport kinesins

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Joseph Atherton ◽  
Irene Farabella ◽  
I-Mei Yu ◽  
Steven S Rosenfeld ◽  
Anne Houdusse ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Conformational Changes ◽  
Catalytic Site ◽  
Fundamental Question ◽  
Force Generation ◽  
Atp Binding ◽  
Cellular Functions ◽  
Microtubule Binding ◽  
Cryo Electron Microscopy ◽  
Adp Release

Kinesins are a superfamily of microtubule-based ATP-powered motors, important for multiple, essential cellular functions. How microtubule binding stimulates their ATPase and controls force generation is not understood. To address this fundamental question, we visualized microtubule-bound kinesin-1 and kinesin-3 motor domains at multiple steps in their ATPase cycles—including their nucleotide-free states—at ∼7 Å resolution using cryo-electron microscopy. In both motors, microtubule binding promotes ordered conformations of conserved loops that stimulate ADP release, enhance microtubule affinity and prime the catalytic site for ATP binding. ATP binding causes only small shifts of these nucleotide-coordinating loops but induces large conformational changes elsewhere that allow force generation and neck linker docking towards the microtubule plus end. Family-specific differences across the kinesin–microtubule interface account for the distinctive properties of each motor. Our data thus provide evidence for a conserved ATP-driven mechanism for kinesins and reveal the critical mechanistic contribution of the microtubule interface.

scholarly journals Loop 1's Role in a Novel Step on the ADP Release Pathway of Smooth Muscle

2010 ◽  
Vol 98 (3) ◽  
pp. 541a
Author(s):  
Justin Decarreau ◽  
Lynn Chrin ◽  
Chris Berger
Keyword(s):  
Smooth Muscle ◽  
Adp Release
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