H Voelkel

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Using 5% ethanol as a deciliating agent, 20 mm colchicine to prevent reciliation and 1 mm amiloride to affect ion fluxes in Paramecium we examined the compartmentation and function of Ca2+ fluxes employing the biosynthesis of cGMP and the stereotypic swimming behavior as indicators for Ca2+ entry. As a function of extracellular Ca2+ Paramecia responded to(More)
The human glutamate transporter EAAT2 (GLT-1) is of major importance for synaptic glutamate reuptake, and reportedly, a candidate gene for neurodegenerative diseases such as amyotrophic lateral sclerosis, Alzheimer's disease and epilepsy. Here we report the polymerase chain reaction (PCR) cloning of two novel EAAT2 transcripts, named EAAT2-C1 and EAAT2-C2,(More)
The ciliate Paramecium tetraurelia secretes large amounts of a cysteine protease into the growth medium, presumably for extracellular food digestion. Two endoprotease isozymes (30 and 33 kDa on SDS/PAGE, respectively), both present in cell homogenates and in spent growth medium, were purified to homogeneity. Peptide sequence analysis revealed that these(More)
OBJECTIVES To investigate if sequence alterations of the excitatory amino acid transporter gene EAAT2 (GLT-1) may be a contributory factor to the pathogenesis of motor system degeneration. EAAT2 serves as a candidate gene as its reduced expression was reported in patients with amyotrophic lateral sclerosis (ALS). Furthermore, neurolathyrism, a motor neuron(More)
TWO novel transcripts of the human excitatory amino acid transporter EAAT2 (GLT-1) were cloned using PCR cloning techniques. Comparative sequence analysis of the 5'-untranslated region (UTR) of five EAAT2 transcripts led to the definition of five putative 5'-untranslated exons that are combined in a variable manner. Alternative splicing is a likely(More)
Calcineurin is a Ca(2+)/calmodulin dependent phosphoprotein phosphatase implicated in a wide range of disorders. Here, we report the cloning of a novel calcineurin A alpha splice variant that lacks both the catalytic and calcineurin B binding domains. Biochemical analysis revealed a stimulating effect on calcineurin activity at low calcium concentrations as(More)
The retinal pigment epithelium (RPE) fulfills important supporting tasks to maintain the visual functions of the sensorineural retina. One major signalling mechanism by which adjacent tissues impinge on the RPE is the adenylyl cyclase (AC)/cAMP pathway. In the RPE, cAMP seems to modulate unique functions such as the phagocytosis of discs shed from the rod(More)
A cDNA of a type 7 adenylyl cyclase isoform was cloned from a bovine retinal pigment epithelium cDNA library using oligonucleotides developed to conserved regions common to mammalian adenylyl cyclases. A 6.7 kb mRNA of very high abundance was uniquely present on Northern blots containing mRNA or total RNA from the pigment epithelium. This transcript was(More)
Mutations in the SOD1 gene are associated with familial amyotrophic lateral sclerosis (fALS). The mechanisms by which these mutations lead to anterior horn cell loss are unknown, however, increased binding of Hsps on the demetallated mutant SOD1 has been described which would make the HSPs unavailable for other purposes, and reduce the SOD1 concentration in(More)