Chromogranins, widespread in endocrine and nervous tissue, bind Ca2+

[摘要]

The proteinaceous components of the secretory vesicle contents isolated from bovine adrenal medulla bind Ca²⁺ (number of binding sites, 152 ± 52 nmol Ca²⁺ per mg protein; dissociation constant, 54 ± 8 μM (n = 5)). SDS-polyacrylamide gel electrophoresis and ⁴⁵Ca²⁺binding of the proteins following their separation and blotting on nitrocellulose revealed that Ca²⁺ binds to chromogranins. Moreover, it was shown that the chromogranins, like other known Ca²⁺-binding proteins, can be specifically stained with a cationic carbocyanine dye. The Ca²⁺-binding function of the chromogranins described here, in conjunction with recent findings concerning Ca²⁺ transport across chromaffin vesicle membranes and the widespread distribution of chromogranins in many different endocrine and nerve cells, points to the general importance of these proteins in the metabolism ofCa²⁺.

[学科分类] 生物化学/生物物理

[关键词] Chromogranin Ca2+ binding Metalloprofein Secretory vesicle