Iodide transport: inhibition by agents reacting at the membrane.

Accumulation of iodide by thyroid tissue is inhibited by two phospholipase A-free proteins from cobra venom, filipin, crude phospholipase C, and lysolecithin. The venom proteins decrease K(+) in tissue but do not significantly affect incorporation of phosphorus-32 into phospholipid or stimulation of this process by thyrotropin. However, filipin and crude phospholipase C, like thyrotropin, do increase phospholipid formation.