Nuclear transport of human DDB protein induced by ultraviolet light.
Human damage-specific DNA-binding (DDB) protein can be purified as a heterodimer (p48 and p127) that binds to DNA damaged by ultraviolet light. We report here the effects of UV irradiation on the cellular localization of each DDB subunit as a function of time using green fluorescent fusion proteins in three diploid fibroblast strains: repair-proficient IMR-90 and two repair-deficient xeroderma pigmentosum group E strains (XP95TO and XP3RO). Although p48 remained in the nucleus after UV irradiation, a dynamic nuclear accumulation of p127 from the cytoplasm was found after 24 h. In IMR-90 cells, the nuclear localization of p127 corresponded to the up-regulation of p48 mRNA and protein levels and of DDB activity. XP3RO cells showed delayed but similar kinetics with less transport, whereas XP95TO cells appeared to have different kinetics, suggesting that these cells exhibit different defects in p127 translocation. We propose that p48 might act as the transporter for nuclear entry of p127 but that a third factor might be necessary for efficient transportation.
Liu
W
W
Division of Biochemistry and Molecular Biology, University of California, Berkeley, California 94720-3202, USA.
Nichols
A F
AF
Graham
J A
JA
Dualan
R
R
Abbas
A
A
Linn
S
S
D002241:Carbohydrates / Q000032:analysis; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism / Q000528:radiation effects*; D003593:Cytoplasm / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects; D019281:Dimerization; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D037102:Lectins; D008164:Luminescent Proteins / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism / Q000528:radiation effects; D014162:Transfection; D014466:Ultraviolet Rays; D014983:Xeroderma Pigmentosum / Q000235:genetics / Q000378:metabolism
D002241:Carbohydrates; C091435:DDB1 protein, human; C117669:DDB2 protein, human; D004268:DNA-Binding Proteins; D037102:Lectins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins