Relapsing Polychondritis

JOHNSON, HAROLD M.

doi:10.1001/archderm.1963.01590230159022

Cited by 9 publications

(2 citation statements)

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“…The above considerations, taken together, lead to the conclusion that the NorpA PLC need be activated by only a few percent of its normal capacity to yield a large and rapid light response from the photoreceptor. In the case of rhodopsin, activation of less than 1% of its normal amount is known to generate a maximal response of the photoreceptor (see, e.g., Johnson and Pak (1986) for Drosophila). In the case of vertebrates, this phenomenon has been attributed to the amplification of the response in the phototransduction cascade (see, e.g., Stryer (1983) and Lolley and Lee (1990)), i.e.…”

Section: Discussionmentioning

confidence: 99%

Molecular, Biochemical, and Electrophysiological Characterization of Drosophila norpA Mutants

Pearn

Randall

Shortridge

et al. 1996

Journal of Biological Chemistry

138

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Inositol phosphate signaling has been implicated in a wide variety of eukaryotic cellular processes. In Drosophila, the phototransduction cascade is mediated by a phosphoinositide-specific phospholipase C (PLC) encoded by the norpA gene. We have characterized eight norpA mutants by electroretinogram (ERG), Western, molecular, and in vitro PLC activity analyses. ERG responses of the mutants show allele-dependent reductions in amplitudes and retardation in kinetics. The mutants also exhibit allele-dependent reductions in in vitro PLC activity levels and greatly reduced or undetectable NorpA protein levels. Three carry a missense mutation and five carry a nonsense mutation within the norpA coding sequence. In missense mutants, the amino acid substitution occurs at residues highly conserved among PLCs. These substitutions reduce the levels of both the NorpA protein and the PLC activity, with the reduction in PLC activity being greater than can be accounted for simply by the reduction in protein. The effects of the mutations on the amount and activity of the protein are much greater than their effects on the ERG, suggesting an amplification of the transduction signal at the effector (NorpA) protein level. Transgenic flies were generated by germline transformation of a null norpA mutant using a P-element construct containing the wild-type norpA cDNA driven by the ninaE promoter. Transformed flies show rescue of the electrophysiological phenotype in R1-R6 photoreceptors, but not in R7 or R8. The degeneration phenotype of R1-R6 photoreceptors is also rescued.

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Section: Discussionmentioning

confidence: 99%

Molecular, Biochemical, and Electrophysiological Characterization of Drosophila norpA Mutants

Pearn

Randall

Shortridge

et al. 1996

Journal of Biological Chemistry

138

View full text Add to dashboard Cite

show abstract

“…Relapsing polychondritis has been the subject of several reports (451,614,649,1294). Although, until this time fewer than 20 cases had been reported in the English language literature, the series from the Mayo Clinic included 14 cases, 4 of which had been seen by the authors during a 1year period (649).…”

Section: Relapsing Polychondritismentioning

confidence: 99%