The subtilisin Carlsberg pro-region is a membrane anchorage for two fusion proteins produced in Bacillus subtilis.

The extracellular serylprotease subtilisin Carlsberg (SubC) of Bacillus licheniformis is produced in a precursor form which includes a signal peptide (sp) and a pro-region. We have constructed a fusion protein in which the sp, pro-region and 38 amino acids (aa) at the N terminus of SubC were joined to the immunoglobulin (Ig) G-binding protein G produced by group G streptococci. The fused SubC::protein G was purified on IgG-Sepharose. IgG-binding material derived from membrane or supernatant fractions had different N termini, indicating that release from the membrane occurred only after removal of the pro-region. The proteolytic pattern was identical when SubC::protein G was produced in Bacillus subtilis 168 wild type or in a protease-deficient strain. The sp cleavage point was also defined in the membrane-derived material.