title: Ribosome-binding protein p34 is a member of the leucine-rich-repeat-protein superfamily.
abstract: Protein p34 is a non-glycosylated membrane protein characteristic of rough microsomes and is believed to play a role in the ribosome-membrane association. In the present study we isolated cDNA encoding p34 from a rat liver cDNA library and determined its complete amino acid sequence. p34 mRNA is 3.2 kb long and encodes a polypeptide of 307 amino acids with a molecular mass of about 34.9 kDa. Primary sequence analysis, coupled with biochemical studies on the topology, suggested that p34 is a type II signal-anchor protein; it is composed of a large cytoplasmic domain, a membrane-spanning segment and a 38-amino-acid-long luminally disposed C-terminus. The cytoplasmic domain of p34 has several noteworthy structural features, including a region of 4.5 tandem repeats of 23-24 amino acids. The repeated motif shows structural similarity to the leucine-rich repeat which is found in a variety of proteins widely distributed among eukaryotic cells and which potentially functions in mediating protein-protein interactions. The cytoplasmic domain also contains a characteristic hydrophilic region with abundant charged amino acids. These structural regions may be important for the observed ribosome-binding activity of the p34 protein.
authors.affiliation: Department of Biosystem Science, Graduate School of Science and Technology, Niigata University, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Ohsumi
authors.forename: T
authors.initials: T
authors.lastname: Ichimura
authors.forename: H
authors.initials: H
authors.lastname: Sugano
authors.forename: S
authors.initials: S
authors.lastname: Omata
authors.forename: T
authors.initials: T
authors.lastname: Isobe
authors.forename: R
authors.initials: R
authors.lastname: Kuwano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D016384:Consensus Sequence; D004247:DNA / Q000737:chemistry / Q000302:isolation & purification; D007930:Leucine / Q000032:analysis*; D008565:Membrane Proteins / Q000032:analysis / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D012313:RNA / Q000378:metabolism; D051381:Rats; D012091:Repetitive Sequences, Nucleic Acid; D012270:Ribosomes / Q000378:metabolism*; D017385:Sequence Homology
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; C083177:ribosome-binding protein p34, rat; D012313:RNA; D004247:DNA; D007930:Leucine