Stability of nucleolar versus non-nucleolar forms of human p14(ARF).
Fusion proteins containing the amino-terminal domain of human p14(ARF) linked to green fluorescent protein are able to bind MDM2 and stabilize p53 without localization in the nucleolus. However, these fusion proteins are inherently unstable, with half-lives considerably shorter than either authentic ARF or chimaeras containing the entire coding domain, both of which are predominantly nucleolar. We present evidence that the unstable fusion proteins are significantly stabilized if redirected to the nucleolus by addition of a basic motif based on the nuclear localization signal of SV40 T-antigen. Moreover, the stability of these proteins can be enhanced by modulating the functions of MDM2 and p53. These data are consistent with a model in which ARF interacts with MDM2 in the nucleoplasm but is consequently subject to proteasomal degradation. Nucleolar localization may serve to store or stabilize ARF.
Cancer Research UK, London Research Institute, Lincoln's Inn Fields, London, WC2A 3PX, UK.
Helen
H
Rodway
Susana
S
Llanos
Janice
J
Rowe
Gordon
G
Peters
D001483:Base Sequence; D002460:Cell Line; D002466:Cell Nucleolus / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D006207:Half-Life; D006801:Humans; D008164:Luminescent Proteins / Q000378:metabolism; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051736:Proto-Oncogene Proteins c-mdm2; D034741:RNA, Small Interfering; D025803:Tumor Suppressor Protein p14ARF / Q000378:metabolism*
D008164:Luminescent Proteins; D019913:Nuclear Localization Signals; D009687:Nuclear Proteins; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D025803:Tumor Suppressor Protein p14ARF; D049452:Green Fluorescent Proteins; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2