title: Unique composition of plastid chaperonin-60: alpha and beta polypeptide-encoding genes are highly divergent.
abstract: Molecular chaperones of the chaperonin family occur in prokaryotes and in plastids and mitochondria. Prokaryotic and mitochondrial chaperonin-60 oligomers (Cpn-60) are composed of a single subunit type (p60cpn-60). In contrast, preparations of purified plastid Cpn-60 contain approximately equal quantities of two polypeptides, p60cpn-60 alpha and p60cpn-60 beta, with slightly different electrophoretic mobilities. We have isolated cDNA clones encoding plastid p60cpn-60 alpha and p60cpn-60 beta polypeptides from Brassica napus and Arabidopsis thaliana. The unexpected degree of sequence divergence observed between p60cpn-60 alpha and p60cpn-60 beta raises questions concerning the structure of the oligomer and the functions of these polypeptides. We have also found an amino acid sequence motif within all p60cpn-60 sequences which resembles the p10cpn-10 sequences.
authors.affiliation: Plant Biotechnology Institute, National Research Council Canada, Saskatoon, Saskatchewan.
authors.forename: R
authors.initials: R
authors.lastname: Martel
authors.forename: L P
authors.initials: LP
authors.lastname: Cloney
authors.forename: L E
authors.initials: LE
authors.lastname: Pelcher
authors.forename: S M
authors.initials: SM
authors.lastname: Hemmingsen
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001937:Brassica / Q000235:genetics; D018833:Chaperonins; D004247:DNA / Q000302:isolation & purification; D005656:Fungal Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D011387:Prokaryotic Cells / Q000187:drug effects; D011506:Proteins / Q000235:genetics*; D012689:Sequence Homology, Nucleic Acid
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D011506:Proteins; D004247:DNA; D018833:Chaperonins