Trimerization of the reovirus cell attachment protein (sigma 1) induces conformational changes in sigma 1 necessary...

The implications of reovirus sigma l protein trimerization on its cell-binding function were investigated. Both monomeric and trimeric forms of sigma l were found to be present when full-length type 3 reovirus Sl transcripts prepared in vitro were translated in rabbit reticulocyte lysates. Pulse-chase experiments demonstrated that monomers were precursors of trimers. However, only the trimeric form was capable of binding to cell surface receptors. Protease and antibody recognition analyses revealed significant structural differences between these two sigma l forms at both the N- and C-termini. Our results suggest that trimerization of protein sigma l is accompanied by extensive conformational changes necessary for its cell attachment function.