 Since these initial discoveries in 1994 and 1995, a host of Importin genes, such as IPO4 and IPO7, have been found that facilitate the import of slightly different cargo proteins, due to their differing structure and locality.A large proportion of the importin-α adaptor protein is made up of several armadillo repeats (ARM) arranged in tandem.These repeats can stack together to form a curved shaped structure, which facilitates binding to the NLS of specific cargo proteins.