Nebulin is a very large actin-binding proteins that is involved in the formation of thin muscle filaments. It is believed that nebulin acts as a thin filament "ruler" that regulates filament length. The nebulin protein consist of repeats of up to 190 nebulin domains and it is the intriguing evolution of these repeats that we are interested in. There are three other protein families that contain nebulin repeats, Nebulette, N-RAP and LASP. Interestingly, we find that a cassette of seven domains seem to have been duplicated in tandem several times in some regions of Nebulin and N-RAP. On the other hand, other parts of the proteins have evolved through duplication of one or two domains. Now the task at hand is understanding the forces that govern these tandem duplications. Therefore, we have compared the domain composition of nebulin containing proteins in a wide range of animals. With a good view of some of the duplications that occur we are now trying to identify the genomic regions were the repeating units have been duplicated. The final aim is to determine if there are any conserved patterns that facilitate duplications.
