title: Subcellular localization and topology of porcine reproductive and respiratory syndrome virus E protein.
abstract: Porcine reproductive and respiratory syndrome virus (PRRSV) open reading frame (ORF) 2a contains a small internal ORF (2b) capable of encoding a protein of 70 or 73 amino acids (aa), termed E protein. The function and biochemical information of the E protein are currently not clear. In the present investigation, it was shown that the E protein was mainly located in the endoplasmic reticulum (ER) and Golgi complex in MARC-145 cells. Deletion studies identified the N-terminal 15 residues as an ER localization sequence of the E protein, besides two other localization sequences within positions 23-50 and 50-73, and the N-myristoylation site significantly affected the subcellular localization of the N-terminal 15 residues. The membrane association assay demonstrated that the E protein was an integral membrane protein embedded in the phospholipid bilayer. However, neither the N-myristoylation site nor the hydrophilic C-terminal domain was essential to the membrane association of the E protein. The topology analysis revealed that this protein had N-terminus oriented toward the cytoplasm and C-terminus toward the ER lumen. Finally, immunofluorescence assay indicated that the E protein colocalized with GP2, GP3, GP4 and M protein in cotransfected cells, but not N protein.
authors.affiliation: Center for Molecular Virology, Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Maorong
authors.initials: M
authors.lastname: Yu
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
authors.forename: Caiwei
authors.initials: C
authors.lastname: Chen
authors.forename: Guangpeng
authors.initials: G
authors.lastname: Ma
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kitamura
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000821:virology; D006056:Golgi Apparatus / Q000378:metabolism / Q000821:virology; D000882:Haplorhini; D008969:Molecular Sequence Data; D019318:Porcine Reproductive and Respiratory Syndrome / Q000378:metabolism / Q000821:virology*; D019316:Porcine respiratory and reproductive syndrome virus / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D021382:Protein Sorting Signals; D021381:Protein Transport; D016415:Sequence Alignment; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D021382:Protein Sorting Signals; D017361:Viral Nonstructural Proteins