Proteolytic Fragments of Chromogranins A and B Represent Major Soluble Components of Chromaffin Granules, Illustrated by Two-Dimensional Proteomics with NH2-Terminal Edman Peptide Sequencin

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• 作者：Jean C. Lee ; Vivian Hook
• 刊名：Biochemistry
• 出版年：2009
• 出版时间：June 16, 2009
• 年：2009
• 卷：48
• 期：23
• 页码：5254-5262
• 全文大小：1047K
• 年卷期：v.48,no.23(June 16, 2009)
• ISSN：1520-4995

文摘

Neuroendocrine chromaffin granules of adrenal medulla represent regulated secretory vesicles that secrete neuropeptides and catecholamines which mediate cell−cell communication for physiological functions. This study addressed the identification of the major proteins in these secretory vesicles that provide dynamic storage and secretion of bioactive molecules. Proteins of the soluble compartment of the vesicles were separated by two-dimensional gels and subjected to NH₂-terminal Edman sequencing for identification and determination of NH₂-termini. Results showed that proteolytic fragments of chromogranin A (CgA) and chromogranin B (CgB) represent the major proteins of these secretory vesicles. These fragments resulted from cleavage of their respective precursor proteins at dibasic and monobasic sites, which is consistent with the known cleavage specificities of prohormone processing enzymes. MALDI-TOF MS analyses of protein spots similar in molecular weight that possessed a range of pI values were represented by molecular forms of CgA and CgB proteins. These findings indicate the high prevalence of endogenous CgA and CgB proteolytic fragments that function in chromaffin secretory vesicles for release of bioactive molecules for cell−cell communication.