Final answer:
Spindle fibers, composed of microtubules, are responsible for the distribution of chromosomes during cell division.
Step-by-step explanation:
The microtubular proteins responsible for the distribution of chromosomes during cell division are spindle fibers. Spindle fibers are composed of microtubules, which are polymers of the tubulin protein. These microtubules form the mitotic spindle and aid in separating the chromosomes during mitosis and meiosis.