Identification of a novel nuclear localization signal in Sam68.
Sam68, a nuclear RNA binding protein, binds to Src and is phosphorylated at tyrosine residues in an M-phase specific manner. Here we identified a stretch of 24 amino acid residues in the COOH-terminal portion of Sam68 which function as a nuclear localization signal. This signal sequence bears no apparent homology to any other known nuclear localization sequence. However, this sequence was found to contain a motif, PPXXR (P, Pro; R, Arg), which is conserved in various RNA binding proteins including hnRNP proteins. Replacement of Arg in this motif with Ala abolished the nuclear accumulation of a GFP fusion protein, suggesting that this residue is important in translocating the protein to the nucleus.
Ishidate
T
T
Department of Oncogene Research, Institute for Microbial Diseases, Osaka University, Suita, Japan.
Yoshihara
S
S
Kawasaki
Y
Y
Roy
B C
BC
Toyoshima
K
K
Akiyama
T
T
D016475:3T3 Cells; D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid
D008164:Luminescent Proteins; D049452:Green Fluorescent Proteins; D016392:Proto-Oncogene Proteins pp60(c-src)