A novel glutelin gene was cloned from a cDNA library of maturing rice seeds (Oryza sativa L. cv Nipponbare). The 2.0kbp insert contained an open reading frame encoding a 510 amino acid polypeptide (Mr 57, 116). This novel glutelin shares 46 to 49% amino acid identity with previously identified rice glutelins. A phylogenetic analysis of cloned glutelins indicates that this gene constitutes a new, fifth class of glutelin gene families. The Asn-Gly processing sequence which is highly conserved in 11S seed storage proteins is replaced by Asn-Val in the sequence of the novel glutelin. The amino acid composition extending 50 residues both upstream and downstream of the Asn-Val site was less hydrophilic than in other glutelins. The N-terminal half corresponding to the acidic domains of other glutelins possesses a higher pI value (7.46) than found in other glutelins. Expression of the gene was detected in maturing seeds, but not in roots or leaves.