Analysis of the retention signals of two resident luminal endoplasmic reticulum proteins by in vitro mutagenesis.
Protein disulfide isomerase (PDI, ERp59), ERp72, and ERp61 are luminal proteins of the endoplasmic reticulum (ER) that are characterized by the presence of sequences corresponding to the active site regions of PDI. Each one of these proteins possesses a different COOH-terminal tetrapeptide ER retention signal. In order to investigate what other tetrapeptide sequences could serve as retention signals and to determine to what extent the function of the retention signal is modulated by the protein carrying the signal, we have constructed a set of mutants of two of these resident ER proteins, PDI and ERp72. In each of these proteins, the wild type tetrapeptide sequences were replaced by each member of the set of the 12 possible combinations consisting of (K,R,Q)-(D,E)-(D,E)-L. Analysis of the efficiency of retention of the variant proteins when each was transiently expressed in COS cells showed that the retention efficiencies vary with both the COOH-terminal sequence and with the protein that carries this sequence.
Haugejorden
S M
SM
Department of Microbiology, St. Louis University School of Medicine, Missouri 63104.
Srinivasan
M
M
Green
M
M
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D007535:Isomerases / Q000235:genetics*; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D016296:Mutagenesis; D019704:Protein Disulfide-Isomerases
D008562:Membrane Glycoproteins; C062477:endoplasmic reticulum glycoprotein p72; D007535:Isomerases; D019704:Protein Disulfide-Isomerases