Disclosed is a vector comprising each of the following elements arranged sequentially to form a module open reading frame, said vector comprising a) a first restriction site that codes for a first group of amino acids, wherein the first group of amino acids comprises at least two amino acids； b) a first open reading frame coding for a polypeptide of interest, wherein the coding sequence of the polypeptide of interest is in frame with the coding sequence of at least two amino acids of the first restriction site； c) a second restriction site that codes for a second group of amino acids, wherein the second group of amino acids comprises at least two amino acids, wherein the coding sequence of the second group of amino acids of the second restriction site is in frame with the coding sequence of the polypeptide of interest of the first open reading frame, and wherein the polynucleotide sequence of the second restriction site is not the same as the polynucleotide sequence of the first restriction site； d) a spacer polynucleotide sequence, wherein the spacer polynucleotide sequence codes for at least three spacer amino acids, and wherein the coding sequence for the spacer sequence is in frame with the polynucleotide sequence of the second restriction site； and e) a third restriction site that codes for a third group of amino acids, wherein the third group of amino acids comprises at least two amino acids, wherein the coding sequence of the third group of amino acids of the third restriction site are in frame with the coding sequence of the at least three spacer amino acids and wherein the polynucleotide sequence of the third restriction site is not the same as the polynucleotide sequence of the first restriction site and the third restriction site is not the same as the polynucleotide sequence of the second restriction site, wherein elements (a) through (e) are in-frame linked to one another to form the module open reading frame, wherein the first restriction site is susce
