Membrane proteins of catecholamine-storing vesicles in adrenal medulla and sympathetic nerves.

Abstract

The hormones of the adrenal medulla are stored in a specialized cell particle, the chromaffin granule. Since these organelles can be easily isolated, their biochemical characterisation is already well advanced (see Ref. 26). Less is known about the biochemical properties of the catecholamine-storing vesicles of sympathetic nerve (see Ref. 21). It has, however, already been shown that the vesicles of splenic nerve have two proteins in common with the medullary granules. One of these proteins, which has been called chromogranin A (5, 25), was first isolated from the soluble lysate of chromaffin granules (10, 29, 30). Its presence in the vesicles of bovine splenic nerve has been shown by immunological methods (3, 6, 9, 15). A second protein, common to both storage organelles, is the enzyme dopamine β-hydroxylase (6, 16, 21). It would not be surprising if the synaptic vesicles isolated from brain also have properties similar to those of the catecholamine storing vesicles of the peripheral tissues. Thus, results obtained on these catecholamine storing organelles might help to elucidate the biochemical and functional properties of the complex mixture of isolated synaptic vesicles which store several transmitters, only one of them being noradrenaline.