Vector constructs for expression of two or more functional proteins or polypeptides under operative control of a single promoter and methods of making and using the same are described. The vectors comprise a self-processing cleavage site between each respective protein or polypeptide coding sequence. The vector constructs include the coding sequence for a self-processing cleavage site and may further include an additional proteolytic cleavage sequence which provides a means to remove the self processing peptide sequence from expressed protein(s) or polypeptide(s). The vector constructs find utility in methods for enhanced production of biologically active proteins and polypeptides in vitro and in vivo.