FIG 8.

Model of influenza virus protein distribution in an infected cell membrane. Shown is a graphic representation of the distributions of the HA, NA, M1, M2, and NP proteins in the membrane of an influenza virus-infected cell. While some pairs of proteins, such as HA-M2, NA-NA, M2-M1, and NP-M1, cocluster, other protein pairs, such as HA-M1, NA-M2, NP-HA, and M2-NP, may be brought together at the site of budding by indirect protein or lipid interactions. For instance, the colocalization of M2 and NP may be facilitated by both proteins coclustering with M1. While HA, NA, and M2 are integral membrane proteins, both M1 and NP are represented by open symbols to denote that they are associated with the cytoplasmic face of the plasma membrane.