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Photosynthetic organisms have developed multiple protective mechanisms to survive under high-light conditions. In plants, one of these mechanisms is the thermal dissipation of excitation energy in the membrane-bound chlorophyll antenna of photosystem II. The question of whether or not cyanobacteria, the progenitor of the chloroplast, have an equivalent(More)
The water and solute transporting properties of the epidermis have been proposed to be important determinants of skin moisture content and barrier properties. The water/small solute-transporting protein aquaporin-3 (AQP3) was found by immunofluorescence and immunogold electron microscopy to be expressed at the plasma membrane of epidermal keratinocytes in(More)
BACKGROUND Mechanoreceptors contain compliant elements, termed "gating springs," that transfer macroscopic stimuli impinging on the cells into microscopic stimuli that open the mechanosensitive channels. Evidence for gating springs comes from mechanical experiments; they have not been identified molecularly or ultrastructurally. RESULTS We show that the(More)
CHIP28 is a major water transporting protein in erythrocytes and plasma membranes in kidney proximal tubule and thin descending limb of Henle. Chinese hamster ovary cells were stably transfected with the coding sequence of cloned rat kidney CHIP28k using expression vectors containing cytomegalovirus or Rous sarcoma virus promoters. Clonal cell populations(More)
One of the key questions in biology is how the metabolism of a cell responds to changes in the environment. In budding yeast, starvation causes a drop in intracellular pH, but the functional role of this pH change is not well understood. Here, we show that the enzyme glutamine synthetase (Gln1) forms filaments at low pH and that filament formation leads to(More)
CHIP28 is an integral membrane protein that has been identified as the erythrocyte water channel and that is also expressed in the kidney. Antibodies against erythrocyte CHIP28 were used to localize this protein along the rat urinary tubule. By Western blotting, CHIP28 was detected in kidney plasma membrane and endosome fractions. With the use of(More)
The aquaporins (AQPs) are a family of homologous water-channel proteins that can be inserted into epithelial cell plasma membranes either constitutively (AQP1) or by regulated exocytosis following vasopressin stimulation (AQP2). LLC-PK1 porcine renal epithelial cells were stably transfected with cDNA encoding AQP2 (tagged with a C-terminal c-Myc epitope) or(More)
Channel forming integral protein of 28 kD (CHIP28) functions as a water channel in erythrocytes, kidney proximal tubule and thin descending limb of Henle. CHIP28 morphology was examined by freeze-fracture EM in proteoliposomes reconstituted with purified CHIP28, CHO cells stably transfected with CHIP28k cDNA, and rat kidney tubules. Liposomes reconstituted(More)
In this study we analyzed the expression of aquaporin-4 (AQP4) in mammalian skeletal muscle. Immunohistochemical experiments revealed that affinity-purified AQP4 antibodies stained selectively the sarcolemma of fast-twitch fibers. By immunogold electron microscopy, little or no intracellular labeling was detected. Western blot analysis showed the presence(More)
In this paper we address the difficult problem of parameter-finding in image segmentation. We replace a tedious manual process that is often based on guess-work and luck by a principled approach that systematically explores the parameter space. Our core idea is the following two-stage technique: We start with a sparse sampling of the parameter space and(More)