Association of HSP70 with the adenovirus type 5 fiber protein in infected HEp-2 cells

Although maximal synthesis of HSP70 is induced early (6–12 hr) after adenovirus type 5 (Ad5) infection of HEp-2 or HeLa cells, the total amount of HSP70 appears to be increased at late times of infection (18–24 hr). Since virion structural proteins also accumulate at these times, we investigated the possible interaction between Ad5 structural proteins and HSP70 by immunoprecipitation of infected cell extracts with antibodies to either ATP-affinity-purified HSP70 or to CsCl-gradient-purified Ad5 virions. We found that HSP70 and a 62-kDa Ad-specific protein coimmunoprecipitated from infected cell extracts. Antibody which recognizes one of these two proteins does not cross-react with the other. Thus, the association between HSP70 and the 62-kDa protein appears specific. Using different antisera to specific adenovirus structural proteins, we have identified the 62-kDa protein as the Ad5 fiber protein.