Domain structure of a mammalian myosin I beta.

Reizes, Ofer; Baryłko, Barbara; Li, Cai; Südhof, Thomas C.; Albanesi, Joseph P.

doi:10.1073/pnas.91.14.6349

Cited by 55 publications

(58 citation statements)

References 40 publications

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“…A dominantnegative Myo1c(T) construct was expressed in cells that were also expressing Myc-GLUT4-CFP. This Myo1c(T) truncated mutant has the ability to bind cargo but is missing the actin binding region and the motor domain (29). As expected, the expression of Myo1c(T) significantly inhibited insulin-stimulated GLUT4 translocation to the cell surface, as assayed by counting cells with anti-Myc rims both in the presence and in the absence of PI 3-kinase activity ( Fig.…”

Section: Resultsmentioning

confidence: 67%

Unconventional Myosin Myo1c Promotes Membrane Fusion in a Regulated Exocytic Pathway

Bose

Robida

Furcinitti

et al. 2004

Molecular and Cellular Biology

152

136

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Glucose homeostasis is controlled in part by regulation of glucose uptake into muscle and adipose tissue. Intracellular membrane vesicles containing the GLUT4 glucose transporter move towards the cell cortex in response to insulin and then fuse with the plasma membrane. Here we show that the fusion step is retarded by the inhibition of phosphatidylinositol (PI) 3-kinase. Treatment of insulin-stimulated 3T3-L1 adipocytes with the PI 3-kinase inhibitor LY294002 causes the accumulation of GLUT4-containing vesicles just beneath the cell surface. This accumulation of GLUT4-containing vesicles near the plasma membrane prior to fusion requires an intact cytoskeletal network and the unconventional myosin motor Myo1c. Remarkably, enhanced Myo1c expression under these conditions causes extensive membrane ruffling and overrides the block in membrane fusion caused by LY294002, restoring the display of GLUT4 on the cell exterior. Ultrafast microscopic analysis revealed that insulin treatment leads to the mobilization of GLUT4-containing vesicles to these regions of Myo1c-induced membrane ruffles. Thus, localized membrane remodeling driven by the Myo1c motor appears to facilitate the fusion of exocytic GLUT4-containing vesicles with the adipocyte plasma membrane.

show abstract

Section: Resultsmentioning

confidence: 67%

Unconventional Myosin Myo1c Promotes Membrane Fusion in a Regulated Exocytic Pathway

Bose

Robida

Furcinitti

et al. 2004

Molecular and Cellular Biology

152

136

View full text Add to dashboard Cite

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“…A retinal cDNA library constructed in Agtl 1 (Clontech) was screened by using the genomic A clone 2 already isolated, which contains 10 exons of the myosin VIIA gene (4 (11,12). The GKTKIFLK C-terminal sequence of this domain is also found in other unconventional myosins (13,14 The C-terminal part of some unconventional myosins includes segments consisting of both positively charged residues and hydrophobic residues, which have been shown to bind negatively charged membranous phospholipids (22)(23)(24). However, the molecular basis of the specific targeting of each tail to a given membrane is unknown and no ligand of any unconventional myosin has yet been identified.…”

Section: Methodsmentioning

confidence: 99%

Human myosin VIIA responsible for the Usher 1B syndrome: a predicted membrane-associated motor protein expressed in developing sensory epithelia.

Weil

Lévy

Sahly

et al. 1996

Proc. Natl. Acad. Sci. U.S.A.

166

147

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“…Myo1c is a class I myosin that is widely expressed in vertebrate tissues (2,3). It consists of a motor domain, a neck or lever arm domain (three or four IQ repeats each of which binds a calmodulin), and a cargo-binding domain (4)(5)(6). In adipocytes Myo1c facilitates glucose transporter recycling in response to insulin (7,8), and in amphibian oocytes Myo1c mediates exocytosis (9).…”

mentioning

confidence: 99%

Calcium sensitivity of the cross-bridge cycle of Myo1c, the adaptation motor in the inner ear

Adamek

Coluccio

Geeves

2008

Proc. Natl. Acad. Sci. U.S.A.

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The class I myosin Myo1c is a mediator of adaptation of mechanoelectrical transduction in the stereocilia of the inner ear. Adaptation, which is strongly affected by Ca 2؉ , permits hair cells under prolonged stimuli to remain sensitive to new stimuli. Using a Myo1c fragment (motor domain and one IQ domain with associated calmodulin), with biochemical and kinetic properties similar to those of the native molecule, we have performed a thorough analysis of the biochemical cross-bridge cycle. We show that, although the steady-state ATPase activity shows little calcium sensitivity, individual molecular events of the cross-bridge cycle are calcium-sensitive. Of significance is a 7-fold inhibition of the ATP hydrolysis step and a 10-fold acceleration of ADP release in calcium. These changes result in an acceleration of detachment of the cross-bridge and a lengthening of the lifetime of the detached M-ATP state. These data support a model in which slipping adaptation, which reduces tip-link tension and allows the transduction channels to close after an excitatory stimulus, is mediated by Myo1c and modulated by the calcium transient. molecular motor ͉ myosin M yosins are actin-based molecular motors that support a variety of cellular functions including muscle contraction and cell migration. There are at least two dozen classes in the myosin superfamily based on analysis of sequences in the catalytic domain (1). Myo1c is a class I myosin that is widely expressed in vertebrate tissues (2, 3). It consists of a motor domain, a neck or lever arm domain (three or four IQ repeats each of which binds a calmodulin), and a cargo-binding domain (4-6). In adipocytes Myo1c facilitates glucose transporter recycling in response to insulin (7,8), and in amphibian oocytes Myo1c mediates exocytosis (9). In the specialized cells of the inner ear, there is considerable evidence that Myo1c acts as a mediator of adaptation of mechanoelectrical transduction in stereocilia (10, 11).Neighboring stereocilia on the hair cells of the inner ear are connected by extracellular tip links that are attached to transduction channels, which in turn are attached to an adaptation-motor complex consisting of Myo1c molecules. The prevailing model for mechanotransduction is that deflection of the stereocilia by sound or motion affects tip-link tension and causes opening or closing of transduction channels through which potassium and calcium ions pass (5, 12, 13). Myo1c sets the transducer sensitivity by moving along the core bundle of actin filaments in the stereocilia until the resting tension in the tip link is at a point where the channels are poised just below the threshold tension required to open the channels (Fig. 1). During an excitatory stimulus, movement of the stereocilia increases tip-link tension, opening the channels. Fig. 1 illustrates how in adaptation the motor/transducer complex responds to increased tension by slipping down the actin cytoskeleton thereby reducing tip-link tension. Alternatively, reduced tension causes Myo1c to ascend the ac...

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Domain structure of a mammalian myosin I beta.

Cited by 55 publications

References 40 publications

Unconventional Myosin Myo1c Promotes Membrane Fusion in a Regulated Exocytic Pathway

Unconventional Myosin Myo1c Promotes Membrane Fusion in a Regulated Exocytic Pathway

Human myosin VIIA responsible for the Usher 1B syndrome: a predicted membrane-associated motor protein expressed in developing sensory epithelia.

Calcium sensitivity of the cross-bridge cycle of Myo1c, the adaptation motor in the inner ear

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