Fig. 2
From: The key amino acids of E protein involved in early flavivirus infection: viral entry
Flavivirus genome organization and membrane topology of mature viral proteins. (A) The genome of flaviviruses. Flaviviruses have a positive-sense (+) RNA genome of approximately 11 kb, which has a cap at the 5’ end. The genome of flaviviruses encodes three structural and seven nonstructural proteins that are translated from a single ORF. 5′ and 3′ UTRs are important for translation and RNA synthesis. Polyprotein cleavage by cellular signal peptidases is indicated by purple marks. Blue arrows denote cleavage by the viral protease NS3 and its cofactor NS2B, whereas the pink mark indicates cleavage by the furin protease. The question mark indicates that NS1 and NS2A are cleaved by an unknown protease. (B) Polyprotein topology and transmembrane domains of flaviviruses. Flavivirus polyprotein is integrated into the ER membrane. The viral proteins prM, E, and NS1 are mainly on the ER luminal side, and C, NS3 and NS5 are mainly on the cytoplasmic side. Proteins NS2A, NS2B NS4A and NS4B have several transmembrane regions spanning across the ER