Entry of M2 into the endoplasmic reticulum Assembly of M2 tetramers Entry of NA into the endoplasmic reticulum Assembly of NA tetramers Glycosylation of NA Entry of HA into the endoplasmic reticulum Accumulation of M1 at the inner leaflet of the lipid bilayer Glycosylation and Folding of HA Trimerization of HA Association of HA into rafts Association of NP into rafts Palmitoylation of cysteine residues on HA in the cis-Golgi network Palmitoylation of cysteine residues on M2 in the cis-golgi network Transport of processed viral proteins to the cell membrane Association of NA into rafts Assembly of Viral Components at the Budding Site Authored: Steel, J, 2007-04-30 20:49:24 Following synthesis on membrane-bound ribosomes, the three viral integral membrane proteins, HA (hemagglutinin), NA (neuraminidase) and M2 (ion channel) enter the host endoplasmic reticulum (ER) where all three are folded and HA and NA are glycosylated. Subsequently HA is assembled into a trimer. HA, NA and M2 are transported to the Golgi apparatus where cysteine residues on HA and M2 are palmitoylated. Furin cleaves HA into HA1 and HA2 subunits and all three proteins are directed to the virus assembly site on the apical plasma membrane via apical sorting signals. The signals for HA and NA reside on the transmembrane domains (TMD) while the sorting signal for M2 is not yet characterized. The TMDs of HA and NA also contain the signals for lipid raft association. Lipid rafts are non-ionic detergent-resistant lipid microdomains within the plasma membrane that are rich in sphingolipids and cholesterol. Examination of purified virus particles indicates that influenza virus buds preferentially from these microdomains. GENE ONTOLOGYGO:0019068 Pubmed0 Reactome Database ID Release 43168316 Reactome, http://www.reactome.org ReactomeREACT_6277 Reviewed: Squires, B, Rush, MG, 2007-04-30 20:48:45 Transport of HA trimer, NA tetramer and M2 tetramer from the endoplasmic reticulum to the Golgi Apparatus PathwayStep3738 PathwayStep3735 PathwayStep3734 PathwayStep3737 PathwayStep3736 PathwayStep3731 PathwayStep3733 PathwayStep3732 PathwayStep3721 PathwayStep3722 PathwayStep3723 PathwayStep3724 PathwayStep3725 PathwayStep3726 PathwayStep3727 PathwayStep3728