Cloning of cDNA encoding a soybean allergen, Gly m Bd 28K

A cDNA clone encoding a soybean allergen, Gly m Ed 28K, has been isolated. The clone has a 1567-bp cDNA insert with a 1419-bp open reading frame and a 148-bp 3'-untranslated region, followed by a polyadenylation tail. The ope n reading frame was shown to encode a polypeptide composed of 473 amino aci ds. The chemically determined amino acid sequences of the peptides obtained from the allergen, including its N-terminal peptide, were shown to be cont ained in the N-terminal region of the amino acid sequence deduced from the cDNA, showing that the first half of the cDNA encodes the allergen with a p receding segment of 21 amino acids. The peptide fragment including the alle rgen was expressed as a fusion protein with glutathione S-transferase in Es cherichia coli and immunoblotted with the sera of soybean-sensitive patient s and the monoclonal antibody against the allergen. Furthermore, homology a nalyses demonstrate that the polypeptide for the cDNA exhibits high homolog y with the MP27/MP32 proteins in pumpkin seeds and the carrot globulin-like protein. This finding suggests that the polypeptide may consist of a 21-am ino acid segment as a part of the signal peptide and the proprotein, which may be converted to two mature proteins. Gly m Ed 28K and a 23-kDa protein, during the development of soybean cotyledons. (C) 2001 Elsevier Science B. V. All rights reserved.