T-Cell Activation and Differentiation

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#Section 3: Genetics, Cellular and Molecular Biology

In skeletal muscle cells, 

a low cytosolic Ca+2 level is maintained by a unique Ca+2 ATPase that continually pumps Ca+2 ions from

the cytosol containing the myofibrils into the SR, establishes a reservoir of Ca+2 in the SR.

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#Section 3: Genetics, Cellular and Molecular Biology

The structure of the sarcomere is maintained by a number of accessory proteins: 

1. CapZ 

2.Tropomodulin

3.Titin 

4.Nebulin

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#Section 3: Genetics, Cellular and Molecular Biology

In the presence of ATP and Ca+2 , the myosin heads extending from the thick

filaments walk toward the (+) ends of the thin filaments.

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#Section 3: Genetics, Cellular and Molecular Biology

Z disk 

Thin actin filaments are assembled with their (+) ends embedded in a densely staining structure

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#Section 3: Genetics, Cellular and Molecular Biology

Each sarcomere contains two major types of filaments: 

Thick filaments (myosin II)

Thin filaments (actin and associated proteins)

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#Section 3: Genetics, Cellular and Molecular Biology

Sarcomere

Within each skeletal muscle cell are many myofibrils consisting of a repeating array of a specialized structure