| The present invention provides a new strategy for preparing an activatable polypeptide arrangement to produce cyclized proteins, characterized in that the strategy can be used to produce cyclized interleukins. The strategy cyclizes the interleukins via intein-mediated protein splicing to prepare functional active interleukin to replace native interleukins in bio-industrial applications. In the strategy, the linker sequence used to connect the N- and C-terminus of the target protein sequence is not related to the protein splicing reaction, thus providing flexibility in the design of cyclized polypeptide. |