PARTICLE-SIZE DOES NOT AFFECT THE RATE OF INTRACELLULAR ROUTING FOR LIGANDS INTERNALIZED BY NON-ADSORPTIVE PINOCYTOSIS

The rate at which three different species of a fluid phase marker (hor seradish peroxidase) reached the lysosomal compartment of mouse LM fib roblasts was compared. Initial observations suggested that the rate wa s a function of particle size. Adjustment of the concentrations of the various species of HRP to equal numbers of physical particles negated the apparent affect. Thus, particle size does not affect the intracel lular routing of a ligand entering fibroblasts by non-adsorptive pinoc ytosis.