STRUCTURE AND FUNCTION OF SURFACTANT PROTEIN D

肺泡表面覆盖着一层薄薄的表面活性物质 这种物质被称为肺表面活性物质。 这种材料， 正常气体交换所必需的，由磷脂和特定的 proteins. 最佳表征的表面活性剂蛋白包括SP-A，和两种 较小的疏水蛋白，SP-B和SP-C。 我们最近净化了 胶原表面活性剂相关糖蛋白。 这 命名为SP-D的蛋白质不同于SP-A和先前描述的 胶原蛋白。 初步实验表明，SP-D具有 碳水化合物结合活性在体外，并有结构 SP-D与C型（钙依赖性）凝集素的同源性。 是我们 假设碳水化合物结合活性介导 SP-D与其它组分的表面活性剂，以及碳水化合物介导的 相互作用有助于这种蛋白质的功能， 体内表面活性剂。 我们提出以下具体目标： 1. 进一步确定特别方案-D的结构; 2. 表征其碳水化合物结合活性; 3. 鉴定表面活性剂中SP-D的配体; 4. 探讨SP-D对表面活性剂的可能贡献 活性和代谢。 这些研究应有助于提供有关下列问题的重要新资料： 肺组织的大分子组成、组织和功能 表面活性剂，以及胶原凝集素的结构和功能。

The alveoli of the lung are covered by a thin layer of surface-active material, referred to as pulmonary surfactant. This material, which is essential for normal gas exchange, consists of phospholipids and specific proteins. The best characterized surfactant proteins include SP-A, and two smaller hydrophobic proteins, SP-B and SP-C. We have recently purified a collagenous surfactant-associated glycoprotein from rat lung. This protein, designated SP-D, is different that SP-A and previously described collagenous proteins. Preliminary experiments indicate that SP-D has carbohydrate-binding activity in vitro, and that there is structural homology of SP-D with the C-type (calcium-dependent) lectins. It is our hypothesis that the carbohydrate-binding activity mediates interactions of SP-D with other components of surfactant, and that carbohydrate-mediated interactions contribute to the function of this protein and pulmonary surfactant in vivo. We propose the following specific aims: 1. To further define the structure of SP-D; 2. To characterize its carbohydrate-binding activity; 3. To identify the ligands for SP-D in surfactant; and 4. To explore the possible contributions of SP-D to surfactant activity and metabolism. These studies should contribute important new information relating to the macromolecular composition, organization, and functions of pulmonary surfactant, and to the structure and function of collagenous lectins.