Day Robert, Gorr Sven Ulrik
Department of Pharmacology, University of Sherbrooke, Sherbrooke, Quebec, Canada J1H 5N4.
Trends Endocrinol Metab. 2003 Jan;14(1):10-3. doi: 10.1016/s1043-2760(02)00011-5.
Secretory granules are found in specialized cell types, including endocrine cells, suggesting that a coordinated programme of gene expression is involved in their biogenesis. Indeed, it has been proposed that chromogranin A (CgA) acts as an on/off switch for secretory granule biogenesis. However, this proposed function is difficult to reconcile with the large body of evidence suggesting that secretory granules exist in the absence of CgA and that cells can synthesize CgA in the absence of secretory granules. Indeed, recent evidence suggests that, rather than a master gene or universal on/off switch, a series of on/off switches combines to induce expression of subsets of secretory granule-associated genes. The assembly of newly synthesized proteins and the inclusion of existing granule proteins would produce functional secretory granules. CgA and related proteins might act as assembly factors in this process.
分泌颗粒存在于包括内分泌细胞在内的特定细胞类型中，这表明基因表达的协调程序参与了它们的生物发生。事实上，有人提出嗜铬粒蛋白A（CgA）作为分泌颗粒生物发生的开关。然而，这一提出的功能难以与大量证据相协调，这些证据表明在没有CgA的情况下分泌颗粒也存在，并且细胞在没有分泌颗粒的情况下也能合成CgA。事实上，最近的证据表明，一系列开关组合起来诱导分泌颗粒相关基因子集的表达，而不是一个主控基因或通用开关。新合成蛋白质的组装以及现有颗粒蛋白的包含会产生功能性分泌颗粒。CgA和相关蛋白可能在此过程中作为组装因子。
