| It was observed that HSPC 021 coelutes with Int 6 and eIF 3 in gel filtration , coimmunoprecipitates with eIF 3 , and is incorporated into eIF 3 both in rabbit reticulocyte lysates and in COS 7 cells . ^^^ A direct protein protein interaction occurs between HSPC 021 and Int 6 , but the analysis of different mutants of HSPC 021 indicated that a larger region of the protein is necessary for incorporation into eIF 3 as compared with binding to Int 6 . ^^^ Taken together , our results establish that HSPC 021 is tightly associated with the mammalian translation initiation factor eIF 3 . ^^^ |