Ion fluxes in lysosomal membranes

这是该项目的第一年，该项目使用多种方法组合来分析溶酶体膜的离子传输特性。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提供服务，尽管在某些组织中它们也用于其他功能。溶酶体功能障碍会导致多种疾病，包括神经功能障碍(溶酶体储存性疾病)和骨化症(骨骼过度钙化)。溶酶体利用三磷酸腺苷驱动的质子泵来维持酸性的管腔pH，并促进其消化功能。这样的泵只有在伴随额外的离子传输以分散由ATPase建立的跨膜电压的情况下才有效。遗传证据表明，这种额外的离子途径是一种CLC类型的阴离子转运体，但功能实验尚未证明这一途径。我们试图确定溶酶体中的离子运输途径，以确定它们的特性，并确定负责的蛋白质。我们最初的工作已经证明，溶酶体膜上存在一种pH依赖的阴离子转运活性，这与功能CLC蛋白的存在是一致的。在接下来的一年里，我们将进一步描述这种转运蛋白的功能特性，并试图证明它是由CLC转运蛋白介导的。

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.