Motor Function and Regulation of Myosin X*

  title={Motor Function and Regulation of Myosin X*},
  author={Kazuaki Homma and Junya Saito and Reiko Ikebe and Mitsuo Ikebe},
  journal={The Journal of Biological Chemistry},
  pages={34348 - 34354}
Myosin X is a member of the diverse myosin superfamily that is ubiquitously expressed in various mammalian tissues. Although its association with actin in cells has been shown, little is known about its biochemical and mechanoenzymatic function at the molecular level. We expressed bovine myosin X containing the entire head, neck, and coiled-coil domain and purified bovine myosin X in Sf9 cells. The Mg2+-ATPase activity of myosin X was significantly activated by actin with lowK ATP. The actin… 

Phospholipid-dependent regulation of the motor activity of myosin X

The following mechanism is proposed: first, the tail inhibits the motor activity of myosin X by intramolecular head-tail interactions to form the folded conformation; second, phospholipid binding reverses the inhibition and disrupts the Folded Conformation, which induces dimer formation, thereby activating the mechanical and cargo transporter activity ofMyosinX.

Motor Property of Mammalian Myosin 10: A Dissertation

The movement directionality of the heterologously expressed myosin 10 was determined to be plus end-directed by the in vitro motility assay with polarity-marked actin filament the authors developed, consistent with the proposed physiological function of myOSin 10 as a plusend-directed transporter inside filopodia.

Mechanism of Action of Myosin X, a Membrane-associated Molecular Motor*

A detailed biochemical kinetic and spectroscopic study on a recombinant myosin X head construct is performed to establish a quantitative model of the enzymatic mechanism of this membrane-boundMyosin, indicating a special mode of actomyosin interaction.

Myosin X Is a High Duty Ratio Motor*

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Mouse Myosin-19 Is a Plus-end-directed, High-duty Ratio Molecular Motor*

It is concluded that Myo19 is a high-duty ratio molecular motor moving to the plus-end of the actin filament, indicating that ADP release is a rate-limiting step for the ATPase cycle of acto-Myo19.

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Class III Myosins

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Myosin-X: a MyTH-FERM myosin at the tips of filopodia

Exciting new studies have begun to reveal the structure and single-molecule properties of this intriguing myosin, as well as its mechanisms of regulation and induction of filopodia.

Localization and Characterization of the Inhibitory Ca2+-binding Site of Physarum polycephalum Myosin II*

It is reported that Ca2+ binds to the first EF-hand of the essential light chain (ELC) subunit of Physarum myosin, suggesting that theCa2+ coordination is different from classical EF-hands; namely, the specific “closed-to-open” conformational transition does not occur in the ELC in response to Ca2+.



Functional expression of mammalian myosin I beta: analysis of its motor activity.

The baculovirus expression system is initiated to characterize a novel myosin I from bovine adrenal gland to suggest that Ca2+ dependent association of calmodulin may function as a regulatory mechanism of myOSin I beta motor activity and that the motor activity of mammalian myos in I is largely different among distinct myosIn I isoforms.

Ca2+-dependent Regulation of the Motor Activity of Myosin V*

Results indicate that inhibition of the motility is due to conformational changes of cal modulin upon the Ca2+ binding to the high affinity site but is not due to dissociation of calmodulin from the heavy chain.

Truncation of a Mammalian Myosin I Results in Loss of Ca2+-sensitive Motility*

Results indicate that Ca2-induced calmodulin dissociation from MI130 in the presence of actin is not from the first IQ domain, and velocity is not affected by the length of the IQ region, and the Ca2+ sensitivity of actIn translocation exhibited by MI130 involves 1 or more of the other 5 IQ domains and/or the carboxyl tail.

Characterization of the motor and enzymatic properties of smooth muscle long S1 and short HMM: role of the two-headed structure on the activity and regulation of the myosin motor.

The depression of the Mg(2+)-ATPase activity of myosin at low ionic strength, characteristic of the 6S-10S transition of smooth muscleMyosin, is abolished with the monomer form, suggesting that the association of the two heads is critical for the 6s-10s transition.

The kinetic mechanism of myosin V.

Myosin V is tuned for processive movement on actin and will be capable of transporting cargo at lower motor densities than any other characterized myosin, in that ADP release is the rate-limiting step for the actin-activated ATPase cycle.

Kinetic Characterization of a Monomeric Unconventional Myosin V Construct*

An expressed, monomeric murine myosin V construct composed of the motor domain and two calmodulin-binding IQ motifs (MD(2IQ)) was used to assess the regulatory and kinetic properties of this

Purification and characterization of a mammalian myosin I.

Results indicate that mammalian myOSin I is more closely related to myosin I from the avian intestinal brush border than to the enzymes isolated from the protozoans Acanthamoeba and Dictyostelium.

Myosin-X, a novel myosin with pleckstrin homology domains, associates with regions of dynamic actin.

The full-length cDNA sequences of human and bovine myosin-X are reported as well as the first characterization of this protein's distribution and biochemical properties, suggesting that this novel unconventionalMyosin plays a role in regions of dynamic actin.

An unconventional myosin heavy chain gene from Drosophila melanogaster

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