Isolation and sequencing of a cDNA clone encoding a 20-kDa protein with trypsin inhibitory activity.

The amino acid sequence of a novel trypsin inhibitor (p20) was completed by the molecular cloning of the protein in cultured soybean cells. The clone nucleotide contains an open reading frame encoding a polypeptide of 206 amino acids that shows 45-50% sequence homology to members of the Kunitz-type trypsin inhibitor family. The p20 transcript is expressed in the roots, stems and leaves of soybean seedlings. DNA gel blot analyses show that the p20 in soybean is encoded by a single gene, and that this gene may not contain an intron.