title: Mass spectrometric analysis of expression of ATPase subunits encoded by duplicated genes in the 19S regulatory particle of rice 26S proteasome.
abstract: The 26S proteasome consisting of a 20S proteasome and a pair of 19S regulatory particles (RP) plays important roles in degradation of the ubiquitinated protein in eukaryotic cells. The RP consists of six different ATPase subunits and, at least, 11 non-ATPase subunits. In rice, we previously identified duplicated genes encoding four ATPase subunits, OsRpt1, OsRpt2, OsRpt4, and OsRpt5. In this study, the genomic sequences of all rice ATPase subunits were identified from the rice genome database and the genomic structure of ATPase subunit genes was determined. The rice RP was purified, and the ATPase subunit isoforms encoded by three pairs of duplicated genes, OsRpt2a/OsRpt2b, OsRpt4a/OsRpt4b, and OsRpt5a/OsRpt5b, were identified in RP by using electrospray ionization quadrupole time-of-flight mass spectrometry. The relative amounts and the expression patterns of these ATPase subunit isoforms in the bran were found to be different from those of the callus, suggesting the presence of multiform 19S regulatory particles engaged in the tissue-specific protein metabolism.
authors.affiliation: Kihara Institute for Biological Research/Graduate School of Integrated Science, Yokohama City University, Maioka 641-12, Totsuka, Yokohama 244-0813, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Shibahara
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kawasaki
authors.forename: Hisashi
authors.initials: H
authors.lastname: Hirano
mesh_terms: D000251:Adenosine Triphosphatases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D000595:Amino Acid Sequence; D010450:Endopeptidases / Q000096:biosynthesis* / Q000737:chemistry / Q000235:genetics*; D040461:Gene Components / Q000235:genetics; D020440:Gene Duplication; D005796:Genes / Q000235:genetics; D007527:Isoenzymes / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology* / Q000235:genetics*; D046988:Proteasome Endopeptidase Complex; D021122:Protein Subunits; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods
chemical_list: D007527:Isoenzymes; D021122:Protein Subunits; D010450:Endopeptidases; D046988:Proteasome Endopeptidase Complex; C119011:26S proteasome non-ATPase regulatory subunit 13; D000251:Adenosine Triphosphatases