In class, we learned about different types of cytoskeletal filaments. We covered intermediate, actin, and microtubules. Intermediate filaments are only found in some animals, have a high tension capacity, and are made up of 8 tetramers stacked on top of each other. They have no directional polarity. Since they do not have polarity, they do not have any motor proteins. They also have no DNA triphosphate on them, so they are not dynamic filaments.
Actin filaments are highly dynamic and easily reorganized. They are 9 nanometers in diameter. Their subunits are called G actin and when in a polymer it is called F actin. A free actin subunit is bound to ATP while in the polymer it is bound to ADP instead. It also goes under a conformational change when incorporated into a filament. Actin has directional polarity where new subunits can be added or taken from each side. The plus end grows and shrinks faster than the minus end in that respect.
Microtubules themselves have a negative charge and are 25-30 nanometers in diameter, forming hollow tubes, The subunit is a heterodimer of alpha tubulin and beta tubulin. It has directional polarity where the beta tubulin faces the plus end and alpha tubulin faces the minus end. Microtubules are dynamic and rearrange into mitotic spindle during mitosis or can form cilia for cell movement. With its polarity, it also has motor proteins going along it. Dyenin is a minus end motor protein and kinesis is a plus end motor protein.