Colloidal gold-labeled insulin complex

Abstract

Biologically active insulin gold complex was used as an ultrastructural marker to study insulin binding sites, uptake, and internalization in isolated rat adipocytes. The preparation conditions for monodispersed particles, ca. 16 nm in diameter and loaded with approximately 100 insulin molecules, are reported. The complex is stable for at least six weeks. Single particles or small clusters were scattered across the cell membrane. The distribution of unbound receptors seemed to be independent of the extensive system of pre-existing surface connected vesicles in adipocytes. The uptake of particles took place predominantly via non-coated pinocytotic invaginations; clathrin-coated pits did not seem to be important for this process. Lysosome-like structures contained aggregates of 10-15 particles. These data suggest that insulin gold complex is a useful marker for the specific labeling of insulin binding sites.

Immunogold labelling of neuroendocrine peptides with special reference to antibody specificity and multiple staining techniques

“…Immunogold methods have contributed greatly to our knowledge in this respect. In addition, it has proven possible to prepare receptor-active gold conjugates of neuropeptides, and such tools may be useful in receptor tracking at both the light-and electron-microscopic level (Handley and Chien 1983;Moll et al 1986;von Banchet and Hoppelmann 1995). These methods will no doubt continue to contrib-ute to the neuroendocrine field.…”