The chromaffin vesicle and the energetics of storage organelles.

In the chromaffin vesicle, energy for amine transport is provided by a proton-translocating adenosine triphosphatase. The ATPase pumps protons into the vesicle; a pair of protons is then exchanged for each catecholamine taken up. In terms of transport, the adrenal chromaffin vesicle is an important model for non-mitochondrial organelles of all types. These organelles include adrenergic synaptic vesicles, other secretory and neurotransmitter storage vesicles, and lysosomes and other intracellular organelles as well. The membranes of these organelles all possess an ATPase that pumps H+ ions into the vesicles. This proton pump presumably drives the transport of ions and molecules into the organelle and powers other energy-requiring functions of the membrane.