title: Isolation and characterization of two distinct cDNA clones encoding corn seed cysteine proteinases.
abstract: We obtained two cDNA clones encoding corn seed cysteine proteinases (CCP1 and CCP2). Sequence analysis showed that CCP1 consists of 371 amino acid residues, in a prepro-protein form, with two unique short insertions in the mature protein region that are not found in papain or other common CPs. CCP2 consists of 360 amino acid residues with a vacuole sorting signal in the pro-sequence region. An amino acid sequence similarity of 42% was found between the mature protein region of CCP1 and that of CCP2. Although CCP1 is highly homologous to pea 15a CP (72%) and Arabidopsis thaliana RD 19 CP (79%), both of which are known to be induced only when the plant is exposed to a dehydrated environment, it showed very low homologies to other known cysteine proteinases (38-43%). CCP2 showed as much as 87% and 89% identity to rice oryzain gamma and barley aleurain, respectively. We also observed that the CCP1 mRNA is expressed in ripened corn seeds, although its expression reaches a maximum 5 days after the onset of germination. On the other hand, the CCP2 mRNA is expressed only during germination, with maximum expression at the 3-day stage. These results suggest the presence of at least two cysteine proteinases playing differential roles in the corn seeds.
authors.affiliation: Laboratory for Food Science, Atomi Junior College, Tokyo, Japan.
authors.forename: C
authors.initials: C
authors.lastname: Domoto
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Abe
authors.forename: K
authors.initials: K
authors.lastname: Abe
authors.forename: S
authors.initials: S
authors.lastname: Arai
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D003546:Cysteine Endopeptidases / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000302:isolation & purification*; D018525:Germination; D008969:Molecular Sequence Data; D012333:RNA, Messenger / Q000302:isolation & purification; D012639:Seeds / Q000201:enzymology; D017386:Sequence Homology, Amino Acid; D003313:Zea mays / Q000201:enzymology*; D015028:Zein / Q000378:metabolism
chemical_list: D018076:DNA, Complementary; D012333:RNA, Messenger; D015028:Zein; D003546:Cysteine Endopeptidases