Gel electrophoresis of soluble and insoluble proteins of noradrenergic vesicles from ox splenic nerve: A comparison with proteins of adrenal chromaffin granules

Abstract

Polyacrylamide gel electrophoresis of a soluble extract of purified large dense-cored vesicles (noradrenergic vesicles) from ox splenic nerve revealed 13 proteins, 7 of which had mobilities close to those of seven of the soluble proteins in adrenal chromaffin granules. Two of these proteins had the same mobilities as dopamine β-hydroxylase and chromogranin A, respectively. The relative staining intensities of the latter two proteins were different: in noradrenergic vesicles, there was more dopamine β-hydroxylase than chromogranin A; whereas in chromaffin granules, chromogranin A was the major protein. Gel electrophoresis of the water-insoluble proteins of noradrenergic vesicles, dissolved in sodium dodecylsulphate, revealed 5 proteins, 5 of which had mobilities close to those of 5 proteins present in the membranes of chromaffin granules. Three of these proteins had mobilities similar to those of dopamine β-hydroxylase, chromogranin A and chromomembrin B, respectively. One of the proteins was probably serum albumin, which was also present as a contaminant in the soluble extract of noradrenergic vesicles. These findings are consistent with earlier studies in which dopamine β-hydroxylase, chromogranin A and chromomembrin B have been identified as constituents of noradrenergic vesicles by enzymatic or immunochemical assay methods. They also indicate further qualitative similarities between the noradrenergic vesicle and the chromaffin granule, in that a total of 7 soluble and 5 insoluble proteins might be common to both particles. However, gel electrophoresis also confirms that quantitative differences exist between the relative proportions of the soluble proteins and shows that dopamine β-hydroxylase is the major soluble protein of the noradrenergic vesicles isolated from splenic nerve trunks.