Singh G, Singal S, Katyal S L, Brown W E, Gottron S A
Department of Pathology, University of Pittsburgh School of Medicine, Pennsylvania.
Exp Lung Res. 1987;13(3):299-309. doi: 10.3109/01902148709069595.
A protein of molecular weight about 10,000 (Clara cell protein C) present in lung lavage fluid and specific to Clara cells has been shown to have three isotypes. The isotypes have been individually isolated and purified by a combination of molecular sieving, ion exchange chromatography, column chromatofocusing, and reverse phase chromatography. The protein was monitored by immunoblotting and its purity tested by silver staining of the gel following sodium dodecyl sulfate-polyacrylamide gel electrophoresis. About 33.7% of the 10-kDa protein present in starting rat lavage was recovered in final pure preparation. The 10-kDa Clara cell protein amounted to 0.38% of the total protein in rat lung lavage fluid. The three isotypes were present in a ratio of 1.0:2.8:8.8, the amounts increasing with decreasing pI. None of the isotypes bound to concanavalin A. The amino acid compositions of the three isotypes were similar and were remarkable in that the contents of leucine, glutamic acid, aspartic acid, serine, and proline were high, tyrosine was present in low amounts, and methionine and histidine were absent.
存在于肺灌洗液中且对克拉拉细胞具有特异性的一种分子量约为10,000的蛋白质（克拉拉细胞蛋白C）已被证明有三种同种型。这些同种型已通过分子筛、离子交换色谱、柱色谱聚焦和反相色谱相结合的方法分别分离和纯化。通过免疫印迹监测该蛋白质，并在十二烷基硫酸钠 - 聚丙烯酰胺凝胶电泳后通过凝胶银染测试其纯度。在最终的纯制剂中回收了起始大鼠灌洗液中存在的10-kDa蛋白质的约33.7%。10-kDa克拉拉细胞蛋白占大鼠肺灌洗液中总蛋白的0.38%。这三种同种型的比例为1.0:2.8:8.8，含量随pI降低而增加。没有一种同种型与伴刀豆球蛋白A结合。这三种同种型的氨基酸组成相似，其显著特点是亮氨酸、谷氨酸、天冬氨酸、丝氨酸和脯氨酸的含量较高，酪氨酸含量较低，且不含甲硫氨酸和组氨酸。
