The two cleavages thus generate the 65-nucleotide pre-miRNA composed of the 22 bp (two helical turns) of dsRNA and the top loop.

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#Unit 2. Cellular Organization

When the Ca2+ levels drop:

Myosin LC is dephosphorylated by MLC phosphatase, causing muscle relaxation.

TLS Online TPP Program

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#Unit 2. Cellular Organization

Ca2+ dependence of vertebrate skeletal muscle contraction, depends on :

action potential

specialized accessory proteins Tropomyosin,

Troponin (T, I, and C)

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#Unit 2. Cellular Organization

Myosin 

Actin-based motors powered by ATP hydrolysis.

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#Unit 2. Cellular Organization

Myosins have 

Motor head domain

Lever-arm neck domain

Cargo-binding tail domain

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#Unit 2. Cellular Organization

The first myosin discovered

Myosin II, was isolated from skeletal muscle.

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#Unit 2. Cellular Organization

Three classes of myosins:

Myosin I

Myosin II

Myosin V