CHARACTERIZATION OF PREPROTACHYKININ-B PROCESSING IN HETEROLOGOUS ENDOCRINE CELL-LINES

We have investigated endoproteolytic processing of protachykinin B and regulated release of neurokinin B following transfection into heterol ogous endocrine cell lines, AtT-20 and MING. Both of the transfected c ell lines produced mature neurokinin B and secreted it in response to a secretagogue, 8-Br-cAMP. Northern blot analysis of PC3 and PC2, two recently cloned Kex2-like processing endoprotease, showed that AtT-20 cells expressed PC3 mRNA, while MING cells expressed both PC2 and PC3 mRNAs. These data suggest that protachykinin B is processed to neuroki nin B by at least PC3 within the regulated secretory pathway.