A glycoprotein involved in aggregation of D. discoideum is distributed on the cell surface in a nonrandom fashion favoring cell junctions.

We studied the distribution on the cell surface of a glycoprotein (gp150) involved in the aggregation process of Dictyostelium discoideum. Using immunohemocyanin labeling of intact aggregates and visualization by scanning elecron microscopy (SEM), we found a distribution gradient of gp150 wherein the concentration was enriched at or near sites of cell contact. When the distribution of gp150 on the cell surface was examined with immunoferritin and transmission electron microscopy (TEM), we found that gp150 was closely associated with the plasma membrane.