Localization of the Lys, Asp, Glu, Leu tetrapeptide receptor to the Golgi complex and the intermediate compartment in mammalian cells

We next determined the localization of the KDEL-R in rat exocrine pancreatic acinar cells (PAC), since the morphological aspects of the secretory pathway are well established in these cells (Farquhar and Palade, 1981; Orci et al., 1991; Figure 1. A thawed cryosection of a mouse early spermatid labeled with the anti-KDEL-R. Note the abundance of labeling associated with the cisternae on the cis (C) side of the Golgi stack. The trans/TGN (T) elements, which have extensive regions coated with clathrin in these cells (see Grifliths, 1981) , have only very low levels of label (arrowheads). The elements can also be identified by being directly adjacent to the developing acrosome (A), which overlays the nucleus (N). Bar, 200 nm. Oprins et al., 1993) . Consistent with the results in spermatids, the bulk of the label for the receptor in the PAC was associated with one side of the Golgi stack, both on cisternal, as well as tubulovesicular structures (not shown). The rough ER was very poorly labeled. Since the condensing vacuoles serve as a trans marker in these cells, we could conclude that the bulk of the KDEL-R was associated with the cis side of the Golgi stack of PAC. We also examined the labeling with anti KDEL-R on sections of liver and kidney from both rat and mouse. In both tissues, the bulk of the label was on or close to theiGolgi stack and, as in the pancreas and spermatids, preferentially concentrated on one side of the stack (results not shown).