Intracellular Localization of UDP-Glucuronosyltransferase Expressed from the Transfected cDNA in Cultured Cells

Masahiko Kinosaki, Kazuhiro Sogawa, Yoshiaki Fujii-Kuriyama, Takashi Masuko, Yoshiyuki Hashimoto, Takashi Iyanagi, Tadashi Yamamoto

    Research output: Contribution to journalArticlepeer-review

    11 Citations (Scopus)


    Liver UDP-glucuronosyltransferase (UDPGT) is localized in the endoplasmic reticulum (ER), with its catalytic domain exposed to the lumenal side of the membrane structure. The proteins expressed from the transfected UDPGT cDNA in cultured cells were found to be localized in the ER membrane. Its enzyme activity was in a latent state and was fully expressed in an in vitro assay system when the membrane integrity was disrupted by a detergent, Triton X-100, suggesting that the orientation of the expressed enzyme in the membrane was the same as that of the liver enzyme. To investigate how the expressed UDPGT was retained in the ER, we constructed chimeric plasmids of cDNAs of UDPGT and ErbB2 which is a receptor protein localized in the cell membranes. Analysis of chimeric proteins expressed in the stable transformants of the cultured cells transfected with these plasmids to reveal that the cytoplasmic tail of UDPGT is responsible for the ER retention of the expressed proteins. Deletion and mutation analysis in the cytoplasmic tail of the enzyme demonstrated that the two lysine residues positioned at 3 and 5 from the C-terminus of the molecule are important for conferring the ER residency. Furthermore, the distance of the ER retention signal composed of the two lysine residues from the transmembrane domain may be influential for the efficiency of the ER retention activity.

    Original languageEnglish
    Pages (from-to)41-51
    Number of pages11
    JournalCell structure and function
    Issue number1
    Publication statusPublished - 1993


    • ER retention sequence
    • Endoplasmic reticulum
    • protein sorting
    • protein targeting signal

    ASJC Scopus subject areas

    • Physiology
    • Molecular Biology
    • Cell Biology


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