Heat shock protein 90ß in the Vero cell membrane binds Japanese encephalitis virus

Wang, Yuan; Li, Yan; Ding, Tianbing

HSPs are a class of chaperone proteins that assist other proteins in folding properly, stabilise proteins against heat stress, aid in protein degradation and stabilise many proteins required for tumour growth. They are the most highly conserved and expressed cellular proteins across all species (37) . As their name implies, HSPs protect cells through increased expression from 1 to 2% of the total proteins in unstressed cells to 4-6% in stressed cells upon stimulation by elevated temperatures (38, and refs therein) . HSP90 is one such heat-related chaperone protein and the '90' indicates that it weighs approximately 90 kDa. It is found in bacteria and all eukaryotes, but is absent in archaea (39) , and its cytoplasmic counterpart is essential for cell viability under all conditions in eukaryotes (40) . Mammalian cells feature several HSP90 isoform homologues (such as α1, α2 and β), which are defined by their different coding genes (HSP90AA1, HSP90AA2 and HSP90AB1), subcellular locations (cytosol, endoplasmic reticulum, and mitochondria) (41) , or extracellular presence (42) . Human HSP90α is inducible, mostly forms anti-parallel homodimers, and is 85% identical to the HSP90β amino acid sequence, which is otherwise described as constitutive and a monomer due to several single amino acid mutations in the C-terminal dimerization domain (43) (44) (45) .