disclosed are a genomic dna of human pacap38 ; a dna containing a dna segment coding for human pacap38 ; a dna of human pacap 38 promotor ; a transformant carrying a vector which contains a dna of or further contains a dna coding for a protein downstream from the promotor ; and a method for preparing a protein comprising cultivating the transformant described in the above , accumulating the protein in a culture product , and collecting the resulting protein such as mature pacap 38 . the dna gives human pacap 38 effectively and makes it possible to screen the chemical substance necessary for production of pacap and is applied to experimental animals to understand their brain functions , which serves to elucidate human brain functions . human pacap38 can also be utilized as therapeutic agents about growth and maintenance of human brain nerves .