Alvarez L, Fanjul M, Carter N, Hollande E
Laboratoire de Biologie Cellulaire et Moléculaire des Epithéliums, Université Paul Sabatier, Toulouse, France.
J Histochem Cytochem. 2001 Aug;49(8):1045-53. doi: 10.1177/002215540104900812.
The subcellular distribution of carbonic anhydrase II, either throughout the cytosol or in the cytoplasm close to the apical plasma membrane or vesicular compartments, suggests that this enzyme may have different roles in the regulation of pH in intra- or extracellular compartments. To throw more light on the role of pancreatic carbonic anhydrase II, we examined its expression and subcellular distribution in Capan-1 cells. Immunocytochemical analysis by light, confocal, and electron microscopy, as well as immunoblotting of cell homogenates or purified plasma membranes, was performed. A carbonic anhydrase II of 29 kD associated by weak bonds to the inner leaflet of apical plasma membranes of polarized cells was detected. This enzyme was co-localized with markers of Golgi compartments. Moreover, the defect of its targeting to apical plasma membranes in cells treated with brefeldin A was indicative of its transport by the Golgi apparatus. We show here that a carbonic anhydrase II is associated with the inner leaflet of apical plasma membranes and with the cytosolic side of the endomembranes of human cancerous pancreatic duct cells (Capan-1). These observations point to a role for this enzyme in the regulation of intra- and extracellular pH.
碳酸酐酶II的亚细胞分布，无论是遍布整个细胞质溶胶，还是存在于靠近顶端质膜或囊泡区室的胞质中，都表明该酶在调节细胞内或细胞外区室的pH值方面可能具有不同作用。为了更深入了解胰腺碳酸酐酶II的作用，我们检测了其在Capan-1细胞中的表达及亚细胞分布。我们进行了光镜、共聚焦显微镜和电子显微镜的免疫细胞化学分析，以及细胞匀浆或纯化质膜的免疫印迹分析。检测到一种29kD的碳酸酐酶II通过弱键与极化细胞顶端质膜的内小叶结合。该酶与高尔基体区室的标志物共定位。此外，在用布雷菲德菌素A处理的细胞中，其靶向顶端质膜的缺陷表明它是通过高尔基体进行转运的。我们在此表明，一种碳酸酐酶II与人胰腺癌性胰腺导管细胞（Capan-1）的顶端质膜内小叶及内膜的胞质侧相关联。这些观察结果表明该酶在调节细胞内和细胞外pH值方面发挥作用。
