POSSIBLE ASSOCIATION OF CHAPERONIN-60 WITH SECRETORY PROTEINS IN PANCREATIC ACINAR-CELLS

Assembly and folding of newly synthesized polypeptides, acquisition of their biological active form, and their translocation in different ce llular compartments are processes assisted by molecular chaperones, Be cause particular chaperones have been found to be present along the RE R-Golgi-granule secretory pathway in pancreatic acinar cells, we presu me that they should play important roles in secretion, In the present study, applying double immunogold labeling at the electron microscopic level on rat exocrine pancreas, we have revealed the existence of a t opographical association between Hsp60 and particular pancreatic enzym es along the secretory pathway, The highest association was found for amylase, lipase, and chymotrypsinogen, whereas trypsinogen and carboxy peptidase B showed much lower association values, Immunoprecipitation of isolated zymogen granule content with an anti-Hsp60 antibody appear s to confirm the morphological data, since amylase and lipase were fou nd to co-precipitate with Hsp60, These findings support the hypothesis that Hsp60 is associated with certain pancreatic proteins along the s ecretory pathway, Hsp60 would assist the proper folding and assembly o f pancreatic secretory proteins and could also prevent their autoactiv ation before secretion.