The function of the protein, dystrophin, is to:
a. Anchor actin filaments to the plasma membrane
b. Conduct an action potential to the sarcoplasmic reticulum
c. Form regular arrays of actin filaments within the I-band
d. Regulate the binding of myosin to actin
e. Transport calcium into t-tubules
ANS: A
Dystrophin attaches actin molecules to the dystroglycan complex of the plasma membrane. Mutations in dystrophin cause muscular dystrophy because cells lacking proper attachment of actin to the plasma membrane do not tolerate the stresses of contraction well.
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