Question

In a muscle cell, myosin binds to actin to cause muscle contraction. Researchers have found that rabbit muscle myosin binds to actin from an amoeba. How can this be?

Answer 1

Myosin and actin are protein filaments found in eukaryotes that slide over one another in a series of repetitive events resulting in muscle contraction.

Eukaryotes amoeba and rabbits share a distant common ancestor and their myosin is similar. There is a difference but the actin binding site cannot detect it.