The present invention relates to a nucleic acid containing at least one homing endonuclease site (HE) and at least one restriction enzyme site (X) wherein the HE and X sites are selected such that HE and X result in compatible cohesive ends when cut by the homing endonuclease and restriction enzyme, respectively, and the ligation product of HE and X cohesive ends can neither be cleaved by the homing endonuclease nor by the restriction enzyme. Further subject-matter of the present invention relates to a vector comprising the nucleic acid of the present invention, host cells containing the nucleic acid and/or the vector, a kit for cloning and/or expression of multiprotein complexes making use of the vector and the host cells, a method for producing a vector containing multiple expression cassettes, and a method for producing multiprotein complexes. The invention also relates to a methods of assembling multiple single vectors (“vector entities”) into fusion vectors and to method of disassembling a fusion vector containing multiple of such vector entities into single vectors. The invention is also directed to fusion vectors containing multiple vector entities.