ERGIC-53, a membrane protein of the ER-Golgi intermediate compartment, carries an ER retention motif.
Overlapping cDNAs encoding the entire human ERGIC-53, a 53 kDa membrane protein of the ER-Golgi intermediate compartment, have been isolated and their nucleotide sequence determined. The isolated cDNA is about 2.7 kb in length. The deduced polypeptide chain for ERGIC-53 consists of 510 amino acids (M(r) 54217) including an N-terminal signal sequence of 30 amino acids, a single putative transmembrane segment of 18 amino acids, and a short cytoplasmic domain of 12 amino acids. Surprisingly, the cytoplasmic segment contains two lysines positioned three and four residues from the C-terminus. Such a double lysine motif is known to function as a retention signal for a group of membrane proteins associated with the ER. Expression of a full-length cDNA of ERGIC-53 in Vero cells revealed intracellular localization similar but not always identical to the endogenously expressed ERGIC-53. The presence of an ER retention motif in a protein of the ER-Golgi intermediate compartment has important implications for the retention mechanism mediated by this signal.
Schindler
R
R
Department of Pharmacology, University of Basel, Switzerland.
Itin
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C
Zerial
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Lottspeich
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Hauri
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HP
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation / Q000502:physiology*; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry*; D005815:Genetic Code; D006056:Golgi Apparatus / Q000737:chemistry*; D006801:Humans; D008239:Lysine / Q000032:analysis*; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009841:Oligonucleotides / Q000138:chemical synthesis
D018076:DNA, Complementary; C084004:LMAN1 protein, human; D037241:Mannose-Binding Lectins; D008565:Membrane Proteins; D009841:Oligonucleotides; D008239:Lysine