A DNA, which encodes the following polypeptide (a), (b), (c) or (d): (a) a polypeptide consisting of an amino acid sequence represented by SEQ ID NO: 2 or 4, (b) a polypeptide consisting of an amino acid sequence derived from the amino acid sequence represented by SEQ ID NO: 2 or 4 by deletion, substitution or addition of one or several amino acids, and having hypophosphatemia-inducing activity, phosphate transport-suppressing activity, calcification-suppressing activity or in vivo vitamin D metabolism-regulating activity, (c) a polypeptide consisting of a partial sequence of the amino acid sequence represented by SEQ ID NO: 2, wherein the above partial sequence contains an amino acid sequence at least ranging from the 34.sup.th to 201.sup.st amino acids in the above amino acid sequence, or (d) a polypeptide consisting of a partial sequence of the amino acid sequence represented by SEQ ID NO: 2, wherein the above partial sequence: (i) contains an amino acid sequence ranging from at least the 34.sup.th to 201.sup.st amino acids in said amino acid sequence, (ii) consists of an amino acid sequence derived from the partial sequence by deletion, substitution, or addition of one or several amino acids, and (iii) has hypophosphatemia-inducing activity, phosphate transport-suppressing activity, calcification-suppressing activity or in vivo vitamin D metabolism-regulating activity.