TABLE 4

Effects of an endocytosis inhibitor, selected inhibitors, a metabolic inhibitor, and temperature on the acid-resistant binding of 125I-ADAB and 125I-ADAMB to TM-BBB4 cells

Inhibitors
Concentration
Acid-Resistant Binding
125I-ADAB
125I-ADAMB
% of control
Daverinea 500 μM 57.7 ± 3.6* 44.7 ± 2.0**
Poly-l-lysine 300 μM 23.6 ± 3.7** 31.9 ± 0.9**
Protamine 300 μM 26.1 ± 4.1** 27.7 ± 0.9**
Poly-l-glutamic acid 300 μM 72.8 ± 5.6 90.1 ± 5.0
2,4-Dinitrophenol 1 mM 91.1 ± 7.4 109 ± 7.9
4°C
100 ± 19
129 ± 23

  • 125I-Labeled peptides were incubated with TM-BBB4 at 37 or 4°C for 60 min in the presence of 2,4-dinitrophenol, dansylcadaverine, and selected inhibitors. After the incubation, the cells were washed with phosphate-buffered saline, and then further washed with cold acetate-barbital buffer (pH 3.0) at 4°C for 10 min. After solubilization of cells with 1 N NaOH, radioactivity was counted as a measure of acid-resistant binding. Each value represents the mean ± S.E. of four or more experiments.

  • ↵* p < 0.05

  • ↵** p < 0.01, significantly different from the control

  • ↵ a After preincubation, the medium was replaced with incubation buffer without inhibitor