Tschopp J, Jenne D E, Hertig S, Preissner K T, Morgenstern H, Sapino A P, French L
Institute of Biochemistry, University of Lausanne, Epalinges, Switzerland.
Blood. 1993 Jul 1;82(1):118-25.
Clusterin, a 70-Kd disulfide-linked two-chain plasma glycoprotein circulates in blood as a high-density lipoprotein particle and is highly induced after tissue injury and tissue remodeling. In this study, peripheral blood leukocytes were assayed for clusterin expression. The protein was predominantly detectable in human platelets by immune cytochemistry. The content of clusterin was determined and amounts to 2.5 +/- 1.3 micrograms/10(9) platelets, thus representing about 2% of the blood pool. Clusterin purified from human platelets had the same molecular weight as plasma clusterin under nonreducing conditions and was composed of two disulfide-linked nonidentical subunits of the same size. Both preparations were sensitive to reduction yielding the two subunits of 35 Kd. In contrast to plasma clusterin, the platelet form was not complexed to apolipoprotein A-I. By immunogold labeling, alpha-granule localization of clusterin was observed. Complete release of platelet clusterin occurred at optimal doses of A23187, phorbol myristate acetate (PMA), and thrombin. Because clusterin mRNA was detected by hybridization in situ in bone marrow-derived megakaryocytes, platelet clusterin is most likely produced and packaged into alpha-granules during megakaryocyte development.
簇集素是一种70千道尔顿的二硫键连接的双链血浆糖蛋白，作为高密度脂蛋白颗粒在血液中循环，在组织损伤和组织重塑后被高度诱导。在本研究中，对外周血白细胞进行了簇集素表达检测。通过免疫细胞化学方法，在人血小板中主要可检测到该蛋白。测定了簇集素的含量，为2.5±1.3微克/10⁹个血小板，约占血池的2%。在非还原条件下，从人血小板中纯化的簇集素与血浆簇集素具有相同的分子量，由两个二硫键连接的大小相同的不同亚基组成。两种制剂对还原均敏感，产生35千道尔顿的两个亚基。与血浆簇集素不同，血小板形式的簇集素不与载脂蛋白A-I结合。通过免疫金标记，观察到簇集素在α-颗粒中的定位。在最佳剂量的A23187、佛波酯肉豆蔻酸酯乙酸盐（PMA）和凝血酶作用下，血小板簇集素完全释放。由于通过原位杂交在骨髓来源的巨核细胞中检测到簇集素mRNA，血小板簇集素很可能在巨核细胞发育过程中产生并包装到α-颗粒中。
