BREFELDIN-A INHIBITS THE DELIVERY OF THE POLYMERIC IMMUNOGLOBULIN RECEPTOR TO THE BASOLATERAL SURFACE OF MDCK CELLS

We have studied the effects of brefeldin A (BFA) on the polarized deli very of the polymeric immunoglobulin receptor to the basolateral surfa ce of MDCK cells. Unlike the delivery of several other basolateral mem brane and secretory proteins, the delivery of the polymeric immunoglob ulin receptor from the trans-Golgi network to the cell surface was inh ibited by BFA. The effect of BFA treatment was apparent at 1.0 mug/ml (36% inhibition), and maximal inhibition was observed at 10 mug/ml (70 % inhibition). The delivery of the receptor from the endoplasmic retic ulum to the basolateral surface was even more sensitive to the effect of BFA; delivery was inhibited 95% in cells treated with 1 mug/ml BFA. The selective action of BFA on the basolateral delivery of the polyme ric immunoglobulin receptor suggests that there may be multiple pathwa ys for delivery of proteins to the basolateral cell surface of MDCK ce lls.