Dipeptidyl peptidase IV is sorted to the secretory granules in pancreatic islet A-cells

J Histochem Cytochem. 1993 Jan;41(1):81-8. doi: 10.1177/41.1.8093256.

Abstract

Dipeptidyl peptidase IV (DP IV:EC 3.4.14.5) was localized in endocrine cells of pig pancreas by immunohistochemical and enzyme histochemical methods. Immunolight microscopy with both monoclonal and polyclonal antibodies demonstrated DP IV immunoreactivity in cells located in the peripheral part of the islets of Langerhans. The antigen is enzymatically active, as shown by enzyme histochemical analysis with a synthetic DP IV substrate. By immunoelectron microscopy (immunogold labeling), the labeling of DP IV in the islets was associated with the secretory granules of the A-cells, as identified by double labeling using a monoclonal glucagon antibody as the second primary antibody. These results show that DP IV is sorted to secretory granules in the pig pancreatic islet A-cells. Furthermore, this secretory granule enzyme, as opposed to intestinal brush border DP IV, is suggested to be a soluble protein, since the gold particles appear all over the granules and are not specifically associated with the granule membrane.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Biological Transport
  • Cells, Cultured
  • Cytoplasmic Granules / metabolism*
  • Dipeptidyl Peptidase 4
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / metabolism*
  • Immunohistochemistry
  • Islets of Langerhans / metabolism*
  • Islets of Langerhans / ultrastructure
  • Microvilli / metabolism
  • Swine

Substances

  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
  • Dipeptidyl Peptidase 4