Ion fluxes in lysosomal membranes

这是该项目的第一年，该项目使用多种方法来分析溶酶体膜的离子运输特性。溶酶体是细胞内的细胞器，在大多数细胞中作为消化细胞器，尽管在某些组织中它们被用于其他功能。溶酶体功能紊乱可导致多种疾病，包括神经功能障碍（溶酶体贮积病）和骨质疏松症（骨过度钙化）。溶酶体利用atp驱动的质子泵来维持酸性的腔内pH值并促进其消化功能。这样的泵只有在伴随着额外的离子传输来消散由atp酶建立的跨膜电压时才能有效。遗传证据表明，这一额外的离子途径是clc型阴离子转运体，但功能实验尚未证实这一途径。我们试图确定溶酶体中的离子运输途径，表征它们的性质，并确定负责的蛋白质。我们最初的努力已经证明溶酶体膜中存在ph依赖性阴离子运输活性，与功能性ClC蛋白的存在一致。在接下来的一年里，我们将进一步表征这种转运的功能特性，并试图证明它是由ClC转运体介导的。

This was the first year for this project, which is using a combination of methods to analyze the ion transport properties of lysosomal membranes. Lysosomes are intracellular organelles that serve in most cells as digestive organelles although in some tissues they are used for other functions. Disorders of lysosome function lead to a variety of diseases including neurological dysfunction (lysosomal storage diseases) and osteopetrosis (overcalcification of bone). Lysosomes utilize an ATP-driven proton pump to maintain an acidic luminal pH and facilitate their digestive function. Such a pump can only be effective if accompanied by additional ion transport to dissipate the transmembrane voltage built up by the ATPase. Genetic evidence suggests that this additional ion pathway a ClC-type anion transporter, but functional experiments have not yet demonstrated such a pathway. We seek to identify the ion transport pathways in lysosomes, to characterize their properties, and to identify the responsible proteins. Our initial efforts have demonstrated the presence of a pH-dependent anion transport activity in lysosomal membranes, consistent with the presence of a functional ClC protein. In the upcoming year we will further characterize the functional properties of this transport and attempt to prove that it is mediated by a ClC transporter.