The major glycoprotein of pancreatic zymogen granule membranes ( @entity37669 ) was detected in the medium of acinar cell suspensions from @entity35 pancreas. Its release from the cells was studied in pulse-chase metabolic labeling experiments with radioactive @entity1853 . @entity37669 (apparent Mr = 80 000) was found to be processed to a form of slightly lower apparent Mr (75 000) after about 4 h chase. At about the same time this smaller form of @entity37669 appeared in the medium. These results are in accordance with earlier findings in vivo. At different chase times acinar cells were extracted with Triton X-114 to separate water-soluble proteins from membrane-associated (hydrophobic) proteins. This experiment showed that @entity37669 is slowly converted from a membrane-bound glycoprotein to a soluble glycoprotein after its reduction in apparent molecular mass, causing its detachment from the membrane. Further analysis indicated that the detachment process may occur at the zymogen granule membrane as well as the plasma membrane. Immunocytochemistry on ultrathin cryosections of pancreatic tissue showed that @entity37669 is localized on zymogen granule membranes, plasma membranes and in the acinar lumen. Although in much smaller quantities, @entity37669 is also present in the granule content. Thus, in summary, @entity37669 is synthesized as a true membrane glycoprotein which is gradually processed to a soluble species and is found in the secretion.

Membrane detachment and release of the major membrane glycoprotein of secretory granules in XXXX pancreatic exocrine cells.

@entity35 :: ('10116', 'Species') :: ['rat'] @entity37669 :: ('171459(Tax:10116)', 'Gene') :: ['GP-2'] @entity1853 :: ('MESH:D008715', 'Chemical') :: ['methionine']
@entity35 :: (10116,Species) :: ['rat']
