To provide a polypeptide having ceramidase activity, and a gene encoding thereof useful as an reagent for lipid engineering and as indices for diagnosis of atopic dermatitis, an easy method for detecting the polypeptide and method for detecting the gene as well as a method for detecting atopic dermatitis. A polypeptide having an amino acid sequence as shown in SEQ ID NO: 1 in Sequence Listing, or a polypeptide having an amino acid sequence which has substitution, deletion, addition or insertion of one or more amino acids in the amino acid sequence of SEQ ID NO: 1 and having ceramidase activity; a gene encoding the polypeptide; a gene capable of hybridizing with the above genes under stringent conditions, and encoding a polypeptide having ceramidase activity; an oligonucleotide probe or primer, which is capable of hybridizing under stringent conditions with the above genes or with a gene having a nucleotide sequence complementary thereto; a method for detecting a gene encoding a polypeptide having ceramidase activity, by using the oligonucleotide probe and/or primer; an antibody or a fragment thereof, which is capable of specifically binding to the polypeptide; a method for detecting a polypeptide having ceramidase activity, by using the above antibody or fragment thereof; a method for detecting atopic dermatitis, by the methods.
1. An isolated gene encoding a polypeptide having an amino acid sequence as shown in SEQ ID NO: 1.
2. The isolated gene according to claim 1 , wherein the gene has a nucleotide sequence as shown in SEQ ID NO: 2.
3. An isolated gene capable of hybridizing with the gene of claim 1 under stringent conditions wherein incubation is made at 65° C. for overnight in a solution containing 6×SSC (composition of 1×SSC:0.15M NaCl, 0.015M sodium citrate, pH 7.0), 0.5% SDS, 5×Denhardt's reagent, and 100 mg/ml herring sperm DNA, and encoding a polypeptide having ceramidase activity.
4. A transformant harbouring the isolated gene of claim 1 .
5. A method for producing a polypeptide having ceramidase activity, comprising culturing the transformant of claim 5 4 , and collecting a polypeptide having ceramidase activity from the resulting culture.
6. A transformant harbouring the isolated gene of claim 3 .
7. A method for producing a polypeptide having ceramidase activity, comprising culturing the transformant of claim 6 , and collecting a polypeptide having ceramidase activity from the resulting culture.