Question

what do skeletal, cardiac, and smooth muscle have in common?
transverse tubules
gap junctions
motor units
thick and thin filaments
a bands and i bands

Explanation:

All three types of muscle - skeletal, cardiac, and smooth - are made up of contractile proteins. The thick filaments are mainly myosin and the thin filaments are mainly actin. Transverse tubules are mainly in skeletal and cardiac muscle. Gap junctions are prominent in cardiac and smooth muscle for electrical coupling. Motor units are characteristic of skeletal muscle. A - bands and I - bands are seen in striated (skeletal and cardiac) muscle but not in smooth muscle.

Answer:

thick and thin filaments