Membrane perturbing factor in reticulocyte lysate, which is transiently activated by proteases

Proteases have been used to examine the topology of proteins on various membranes. We reexamined the conditions of protease treatment for rough microsomal membranes and found that proteinase K degraded the lumenal proteins in the presence of reticulocyte lysate. The lysate treated with either heat or N-ethylmaleimide no longer promoted the degradation. The reticulocyte dependent degradation was also observed with papain, trypsin, and elastase. This activity was transiently generated by treating reticulocyte lysate short-term with trypsin. We thus concluded that a membrane perturbing factor(s) must exist in reticulocyte which is transiently activated by protease treatment.