Cox C P, Quissell D O
Thromb Res. 1985 Aug 1;39(3):343-53. doi: 10.1016/0049-3848(85)90230-0.
Among the various naturally occurring substances which induce platelet aggregation and secretion, considerable attention has been focused recently on the phospholipid platelet-activating factor (PAF) derived from a variety of mammalian cells. In this report, we describe a platelet-activating protein, designated RS-PAP, which was isolated and partially purified from the submandibular salivary glands of adult male rats. This material caused a dose-related in vitro activation of washed, [3H]serotonin-labeled platelets from rats, rabbits and humans. The biologic activity of RS-PAP was compared with that of 1-0-alkyl-2-acetyl-sn-glycero-3-phosphorylcholine (AGEPC), a well-characterized representative of the phospholipid platelet-activating factors, and collagen, a potent platelet-stimulating protein. The activation of washed rabbit platelets by RS-PAP required extracellular calcium for both aggregation and secretion of [3H]serotonin, and was not inhibited by indomethacin. Furthermore, RS-PAP was not inhibited by pretreatment with phenylmethylsulfonyl fluoride, iodoacetate, hirudin or an acetylhydrolase which specifically degrades the phospholipid AGEPC. RS-PAP was completely inactivated by heating at 56 degrees C for 20 minutes, by trypsinization and by a phospholipid extraction procedure. Gel filtration on Sephacryl S-200 indicated an approximate molecular weight of 22,000 - 25,000 daltons. Thus RS-PAP appears to be a new platelet-stimulating protein which activates a variety of mammalian platelets.
在各种能诱导血小板聚集和分泌的天然物质中，近来人们相当关注源自多种哺乳动物细胞的磷脂类血小板激活因子（PAF）。在本报告中，我们描述了一种血小板激活蛋白，命名为RS - PAP，它是从成年雄性大鼠的下颌下唾液腺中分离并部分纯化得到的。这种物质能在体外使来自大鼠、兔子和人类的经洗涤的、用[³H]血清素标记的血小板产生剂量相关的激活。将RS - PAP的生物活性与1 - O - 烷基 - 2 - 乙酰 - sn - 甘油 - 3 - 磷酸胆碱（AGEPC，一种特性明确的磷脂类血小板激活因子代表物）以及胶原（一种强效的血小板刺激蛋白）的生物活性进行了比较。RS - PAP对经洗涤的兔血小板的激活，无论是血小板聚集还是[³H]血清素的分泌，都需要细胞外钙，且不受吲哚美辛抑制。此外，用苯甲基磺酰氟、碘乙酸、水蛭素或一种能特异性降解磷脂AGEPC的乙酰水解酶预处理，对RS - PAP均无抑制作用。RS - PAP在56℃加热20分钟、经胰蛋白酶处理以及通过磷脂提取程序后会完全失活。在Sephacryl S - 200上进行凝胶过滤表明其分子量约为22,000 - 25,000道尔顿。因此，RS - PAP似乎是一种能激活多种哺乳动物血小板的新型血小板刺激蛋白。
