Final answer:
All microtubule organizing centers (MTOCs) share the tubulin protein, which is a polymer of protein subunits and evolved from the prokaryotic FtsZ protein. Tubulin and FtsZ are homologous structures that use GTP for energy.
Step-by-step explanation:
The protein component that all microtubule organizing centers, or MTOCs, share is tubulin. MTOCs are crucial for cell division in eukaryotic cells and are involved in organizing the microtubules that help segregate chromosomes during mitosis. Tubulin, which is a polymer of protein subunits, has evolved from its ancestor protein, FtsZ, which is found in prokaryotes. Both tubulin and FtsZ are homologous structures derived from common evolutionary origins. Moreover, both of these proteins utilize guanosine triphosphate (GTP) as an energy source for their assembly and disassembly processes.