title: A SecY homolog in Arabidopsis thaliana. Sequence of a full-length cDNA clone and import of the precursor protein into chloroplasts.
abstract: Proteins are translocated across the thylakoid membrane by two distinct pathways in higher plant chloroplasts, one of which is related to prokaryotic Sec-dependent translocation mechanisms. SecY is an essential, hydrophobic component of the membrane-bound translocase complex in bacteria, and we report here the nucleotide sequence of a full-length cDNA encoding a homolog of SecY from Arabidopsis thaliana. The predicted protein of 551 residues includes an amino-terminal extension of approximately 120 residues when compared with other SecY proteins. The deduced sequence of the mature protein, cpSecY, is 41% identical with SecY from Synechococcus and 33% identical with the Escherichia coli protein. The extension serves to target the protein into chloroplasts; transcription-translation of the cDNA yields a 58-kDa precursor protein which is imported into pea chloroplasts, processed to a product of 46 kDa, and targeted into the thylakoid membrane.
authors.affiliation: Department of Biological Sciences, University of Warwick, Coventry, United Kingdom.
authors.forename: V
authors.initials: V
authors.lastname: Laidler
authors.forename: A M
authors.initials: AM
authors.lastname: Chaddock
authors.forename: T G
authors.initials: TG
authors.lastname: Knott
authors.forename: D
authors.initials: D
authors.lastname: Walker
authors.forename: C
authors.initials: C
authors.lastname: Robinson
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D001692:Biological Transport; D060365:Chloroplast Proteins; D002736:Chloroplasts / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary; D007425:Intracellular Membranes / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011498:Protein Precursors / Q000378:metabolism; D000069816:SEC Translocation Channels; D017386:Sequence Homology, Amino Acid
chemical_list: D029681:Arabidopsis Proteins; D060365:Chloroplast Proteins; D018076:DNA, Complementary; D008565:Membrane Proteins; D010940:Plant Proteins; D011498:Protein Precursors; C000613370:SCY1 protein, Arabidopsis; D000069816:SEC Translocation Channels