Immunological cross-reaction between proteins supposed to be involved in protein secretion inStaphylococcus aureusandBacillus subtilis

An antibody to a 60-kDa protein associated with membrane-bound ribosomes (MBRP) in Staphylococcus aureus was shown to cross-react with a 64-kDa protein in Bacillus subtilis. Evidence is presented suggesting that this Bacillus protein is identical to a 64-kDa protein, possibly involved in protein secretion, described by Horiuchi et al. [Proc. Natl. Acad. Sci. USA 80 (1983) 3287–3291). Both the 60-kDa staphylococcal protein and the 64-kDa Bacillus protein were precipitated as a complex with three other proteins when immunoprecipitated with the staphylococcal MBRP antibody.