Microtubules are composed of tubulin protein dimer subunits. Each NKG2D monomer is associated with DAP10 dimer. These leucine residues tightly bind to leucine residues of another CREB protein forming a dimer. Both dimer and trimer domain-swap structures have been solved. Nucleation is the event that initiates the formation of microtubules from the tubulin dimer. In coordinating solvents, such as ethers and amines, the monomer and dimer are prevalent. It undergoes rapid polymerization, including forming a hemiacetal cyclic dimer. Other diene complexes include (butadiene)iron tricarbonyl and cyclooctadiene rhodium chloride dimer. It is also an excimer molecule but not a homonuclear dimer. This damage is mainly the formation of a thymine dimer. PstI is catalytically active as a dimer. Both, dimer and monomer are co-coordinated by LiCl. In THF its structure is primarily that of a solvated dimer. In 1997 spectroscopic analysis revealed the dimer (or diatomic) absorption features of molecular oxygen. Myosin X is an unconventional myosin motor, which is functional as a dimer.