What question did this study set out to answer?

To determine how loop 1 in the transducer region of mammalian class I myosin (Myo1b) regulates actin affinity, nucleotide access, and ATPase kinetics.

June 27, 2005Journal of Biological ChemistryOpen Access

Loop 1 of Transducer Region in Mammalian Class I Myosin, Myo1b, Modulates Actin Affinity, ATPase Activity, and Nucleotide Access

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To determine how loop 1 in the transducer region of mammalian class I myosin (Myo1b) regulates actin affinity, nucleotide access, and ATPase kinetics.
Engineered baculovirus-expressed Myo1b1IQ chimeras where loop 1 was substituted with loops from other myosins, replaced with glycine, or modified via alanine scanning mutagenesis.
Measured steady-state actin-activated ATPase activity, ATP-induced actin dissociation kinetics, ADP release rates, and actin binding affinity in the presence and absence of ADP.
Loop 1 chimeras exhibited significant changes in steady-state actin-activated ATPase activity and altered actin affinity for both apo-Myo1b1IQ and Myo1b1IQ-ADP compared to wild-type motor.
Biphasic rates of ATP-induced actin dissociation and ADP release were substantially altered in chimeras, demonstrating that loop 1 controls nucleotide pocket accessibility and cross-talk among functional motor domains.

Structured PICO

Population

Chimeric molecules of a truncated form of mammalian class I myosin, Myo1b (Myo1b1IQ), expressed in baculovirus

Intervention

Replacement of loop 1 with loop 1 from other myosins, replacement with glycine, or substitution of amino acids with alanine

Comparator

Wild type Myo1b1IQ

Outcome

Interactions with actin and nucleotide (steady-state actin-activated ATPase activity, rate of ATP-induced dissociation of actin, rate of ADP release, and affinity of actin)surrogate

Loop 1 in mammalian class I myosin Myo1b modulates actin affinity, ATPase activity, and nucleotide access, suggesting it contributes to the load dependence of the motor.

Discussion

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Implication

Hypothesis-generating for myosin motor engineering; leaves open in vivo cardiac relevance and therapeutic translation.

Cite This Study

Clark et al. (2005) studied this question.

synapsesocial.com/papers/6a71470efebe604dd709f8ba https://doi.org/10.1074/jbc.m504698200

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Loop 1 of Transducer Region in Mammalian Class I Myosin, Myo1b, Modulates Actin Affinity, ATPase Activity, and Nucleotide Access

Key Points

Structured PICO

Discussion

Implication

Cite This Study

Loop 1 of Transducer Region in Mammalian Class I Myosin, Myo1b, Modulates Actin Affinity, ATPase Activity, and Nucleotide Access

Key Points

Structured PICO

Discussion

Implication

Cite This Study

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Also Consider