Single vector constructs for expression of an immunoglobulin molecule or fragment thereof and methods of making and using the same are described. The vectors comprise a self-processing cleavage sequence between a first and second immunoglobulin coding sequence allowing for expression of a functional antibody molecule using a single promoter. 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 an expressed immunoglobulin molecule or fragment thereof. The vector constructs find utility in methods for enhanced production of biologically active immunoglobulins or fragments thereof in vitro or in vivo.