[Membrane binding of insulin antigenic sites in the Golgi apparatus of pancreatic B cells].

Ultrastructural immunocytochemistry with anti-insulin antiserum allowed the detection of insulin antigenic sites localized at the inner aspect of the cisternae of the Golgi apparatus in pancreatic B-cells. By contrast, in secretory granules released from the Golgi apparatus, insulin antigenic sites were localized over the granule content but not on the membrane. The demonstration of insulin antigenic sites at the level of the Golgi membranes is compatible with the presence of specific insulin receptors and/or charge interactions between the insulin and the membrane. Binding at this level could in turn be involved in the sorting out of insulin polypeptides destined to be concentrated in secretory granules.