Coilin protein domains Evolutionary conservation at the amino acid level is highest within coilin's N-and C-termini. The middle portion is not conserved and low complexity region and RG box found in human coilin appear to be specific for vertebrates. The first N-terminal 92-amino acid domain was shown to self-interact and to be essential for proper targeting of coilin to CBs. 10-12 The central part contains 2 nuclear localization signals and a putative nucleolar localization