title: The juxtamembrane sequence of cytochrome P-450 2C1 contains an endoplasmic reticulum retention signal.
abstract: The N-terminal signal anchor of cytochrome P-450 2C1 mediates retention in the endoplasmic reticulum (ER) membrane of several reporter proteins. The same sequence fused to the C terminus of the extracellular domain of the epidermal growth factor receptor permits transport of the chimeric protein to the plasma membrane. In the N-terminal position, the ER retention function of this signal depends on the polarity of the hydrophobic domain and the sequence KQS in the short hydrophilic linker immediately following the transmembrane domain. To determine what properties are required for the ER retention function of the signal anchor in a position other than the N terminus, the effect of mutations in the linker and hydrophobic domains on subcellular localization in COS1 cells of chimeric proteins with the P-450 signal anchor in an internal or C-terminal position was analyzed. For the C-terminal position, the signal anchor was fused to the end of the luminal domain of epidermal growth factor receptor, and green fluorescent protein was additionally fused at the C terminus of the signal anchor for the internal position. In these chimeras, the ER retention function of the signal anchor was rescued by deletion of three leucines at the C-terminal side of its hydrophobic domain; however, deletion of three valines from the N-terminal side did not affect transport to the cell surface. ER retention of the C-terminal deletion mutants was eliminated by substitution of alanines for glutamine and serine in the linker sequence. These data are consistent with a model in which the position of the linker sequence at the membrane surface, which is critical for ER retention, is dependent on the transmembrane domain.
authors.affiliation: Department of Molecular and Integrative, Physiology and Cell and Structural Biology, University of Illinois at Urbana-Champaign, 61801, USA.
authors.forename: E
authors.initials: E
authors.lastname: Szczesna-Skorupa
authors.forename: B
authors.initials: B
authors.lastname: Kemper
mesh_terms: D000409:Alanine / Q000737:chemistry; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry* / Q000378:metabolism*; D000072467:Cytochrome P450 Family 2; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D017353:Gene Deletion; D017930:Genes, Reporter; D005973:Glutamine / Q000737:chemistry; D049452:Green Fluorescent Proteins; D006596:Hexosaminidases / Q000494:pharmacology; D008164:Luminescent Proteins / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
chemical_list: D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D005973:Glutamine; D049452:Green Fluorescent Proteins; D003577:Cytochrome P-450 Enzyme System; C096409:CYP2C1 protein, Oryctolagus cuniculus; D000072467:Cytochrome P450 Family 2; D006596:Hexosaminidases; D000409:Alanine