Under what category should myosin come?
Myosin are motor proteins. Microfilaments (AKA actin filaments) are the tracks for Myosin. Filaments of different sizes are the structural components of cells, giving them their shape, rigidity, etc., as well as providing an intracellular network for transport. Myosin walk along these filaments. 

In myocytes (muscle cells), myosin pulls actin filaments towards one another.



Picture from here: https://www.ncbi.nlm.nih.gov/books/NBK9961/