Abstract: The present invention provides a production method of a functional recombinant human hemoglobin, which comprises transforming a yeast of the genus Pichia with an expression vector containing a DNA encoding a human hemoglobin ?-chain (Hb?), which is under regulation of a promoter functional in a yeast of the genus Pichia, and an expression vector containing a DNA encoding a human hemoglobin ?-chain (Hb?), which is under regulation of a promoter functional in a yeast of the genus Pichia, culturing the yeast in a medium, and recovering the human hemoglobin from the obtained culture. The present invention also provides an expression vector containing AOX1 promoter, DNA encoding Hb?, terminator functional in a yeast of the genus Pichia, AOX1 promoter, DNA encoding Hb? and terminator functional in the yeast of the genus Pichia in this order from the upstream side in transcriptional direction.

Abstract: Provided is a high-copy-number, high-expression vector capable of producing a protein having satisfactory functions and activity of the same level as that of a natural form of the protein, in a large quantity and in a simple manner. Also provided is a vector including: (A) a target gene or a cloning site of the target gene, (B) a sequence element necessary for the high copying of the target gene, (C) a sequence element necessary for the expression of the target gene and a methionine aminopeptidase gene; a method of producing the vector; a transformant having the vector introduced therein; and a process for producing a protein using the transformant.