Difference in distribution of membrane proteins between low- and high-density secretory granules in parotid acinar cells
Difference in distribution of membrane proteins between low- and high-density secretory granules in parotid acinar cells
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DOI：
10.1016/j.bbrc.2006.03.130
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发表时间：
2006-05-26
影响因子：
3.1
通讯作者：
Sugiya, H
中科院分区：
文献类型：
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作者：
Fujita-Yoshigaki, J;Katsumata, O;Sugiya, H
分泌颗粒（SG）被认为是作为未成熟的颗粒产生的，并通过其内容物的浓缩而成熟。在这项研究中。腮腺的SG通过Percoll-density gradient离心分离成低、中、高密度颗粒组分，因为有人提出密度对应于成熟程度。电镜观察表明，三个组分中的颗粒非常相似。高密度颗粒的平均直径略大于低密度颗粒，但差异显著。虽然三个组分都含有淀粉酶，说明它们都是SG，但膜蛋白的分布有明显的差异。Syntaxin 6和VAMP 4定位于低密度颗粒部分，而VAMP 2集中在高密度颗粒部分。免疫沉淀与抗突触融合蛋白6抗体引起共沉淀的VAMP 2从中密度颗粒级分没有溶解，但不是从Triton X-100溶解的馏分，而VAMP 4从两个馏分共沉淀。因此，VAMP 2存在于相同的颗粒上，但与突触融合蛋白6和VAMP 4分离，预期突触融合蛋白6和VAMP 4将从未成熟的颗粒中除去。这些结果表明，中密度颗粒是从低密度到高密度颗粒的中间体，并且在成熟过程中，SGs的膜组分通过出芽和融合而动态变化。(c)2006年爱思唯尔公司All rights reserved.
Secretory granules (SGs) are considered to be generated as immature granules and to mature by condensation of their contents. In this study.. SGs of parotid gland were separated into low-, medium-, and high-density granule fractions by Percoll-density gradient centrifugation, since it was proposed that the density corresponds to the degree of maturation. The observation with electron microscopy showed that granules in the three fractions were very similar. The average diameter of high-density granules was a little but significantly larger than that of low-density granules. Although the three fractions contained amylase, Suggesting that they are all SGs, distribution of membrane proteins was markedly different. Syntaxin6 and VAMP4 were localized in the low-density granule fraction, while VAMP2 was concentrated in the high-density granule fraction. Immunoprecipitation with anti-syntaxin6 antibody caused coprecipitation of VAMP2 from the medium-density granule fraction without solubilization, but not from Triton X-100-solubilized fraction, while VAMP4 was coprecipitated from both fractions. Therefore, VAMP2 is present on the same granules, but is separated from syntaxin6 and VAMP4, which are expected to be removed from immature granules. These results suggest that the medium-density granules are intermediates from low- to high-density granules, and that the membrane components of SGs dynamically change by budding and fusion during maturation. (c) 2006 Elsevier Inc. All rights reserved.