Linda L Randall

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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(More)
SecA, a homodimeric protein involved in protein export in Escherichia coli, exists in the cell both associated with the membrane translocation apparatus and free in the cytosol. SecA is a multifunctional protein involved in protein localization and regulation of its own expression. To carry out these functions, SecA interacts with a variety of proteins,(More)
Fundamental to the function of all molecular chaperones is their amazing ability to selectively and rapidly bind proteins in non-native states. Chaperones modulate a kinetic partitioning among the alternative pathways open to polypeptides within a cell, so that the proper pathway is taken. Here we review studies of SecB, a chaperone in Escherichia coli(More)
The folding of maltose-binding protein, a periplasmic protein in Escherichia coli, was shown to proceed through the same rate-limiting step whether folding occurred in the cell under physiological conditions or in vitro in the absence of other proteins. Four species of maltose-binding protein containing aminoacyl substitutions identified as decreasing the(More)
Sensitivity to proteolytic degradation was used to monitor folding of polypeptides in vivo. A correlation between competence for export and lack of stable tertiary structure was established by comparing the kinetics of folding of mutated precursor maltose-binding protein that carries a defective leader peptide with the kinetics of folding of wild-type(More)
SecB, a small tetrameric chaperone in Escherichia coli, facilitates export of precursor polypeptides from the cytoplasm to the periplasmic space. During this process, SecB displays two modes of binding. As a chaperone, it binds promiscuously to precursors to maintain them in a non-native conformation. SecB also demonstrates specific recognition of, and(More)
SecA is found in Escherichia coli both tightly associated with the cytoplasmic membrane where it functions as a translocation ATPase during protein export and free in the cytosol (R. J. Cabelli, K. M. Dolan, L. Qian, and D. B. Oliver, J. Biol. Chem. 266:24420-24427, 1991; D. B. Oliver and J. Beckwith, Cell 30:311-319, 1982; W. Wickner, A. J. M. Driessen,(More)
In all living cells, regulated passage across membranes of specific proteins occurs through a universally conserved secretory channel. In bacteria and chloroplasts, the energy for the mechanical work of moving polypeptides through that channel is provided by SecA, a regulated ATPase. Here, we use site-directed spin labeling and electron paramagnetic(More)
It has been shown that folding of precursor maltose-binding protein of Escherichia coli in vitro is retarded by the leader peptide. We now present evidence that this modulation of folding plays a role during the export of maltose-binding protein in vivo. Maltose-binding protein synthesized in vivo without a leader sequence did not engage the cellular export(More)