Michael Trus

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The association of L-type Ca(2+) channels to the secretory granules and its functional significance to secretion was investigated in mouse pancreatic B cells. Nonstationary fluctuation analysis showed that the B cell is equipped with <500 alpha1(C) L-type Ca(2+) channels, corresponding to a Ca(2+) channel density of 0.9 channels per microm(2). Analysis of(More)
Although N- and P-type Ca2+ channels predominant in fast-secreting systems, Lc-type Ca2+ channels (C-class) can play a similar role in certain secretory cells and synapses. For example, in retinal bipolar cells, Ca2+ entry through the Lc channels triggers ultrafast exocytosis, and in pancreatic beta-cells, evoked secretion is highly sensitive to Ca2+. These(More)
The voltage sensitive N-type calcium channel interacts functionally and biochemically with synaptotagmin (p65). N-type channel interaction with p65 is demonstrated in the Xenopus oocyte expression system, where p65 alters the steady state voltage inactivation of the N-channel, and fully restores the syntaxin-modified current amplitude and inactivation(More)
The membrane topology of alpha 2/delta subunit was investigated utilizing electrophysiological functional assay and specific anti-alpha 2 antibodies. (a) cRNA encoding a deleted alpha 2/delta subunit was coinjected with alpha 1C subunit of the L-type calcium channel into Xenopus oocytes. The truncated form, lacking the third putative TM domain (alpha(More)
Starvation refeeding experiments were conducted in rats to test the hypothesis that adaptation of glucokinase (the high Km component of glucose phosphorylation) could be the major determinant of glucose metabolism of pancreatic islet cells and of glucose-stimulated insulin release. It was found that glucokinase of islet homogenates, glucose use by intact(More)
Syntaxin 1A has a pronounced inhibitory effect on the activation kinetics and current amplitude of voltage-gated Ca(2+) channels. This study explores the molecular basis of syntaxin interaction with N- and Lc-type Ca(2+) channels by way of functional assays of channel gating in a Xenopus oocytes expression system. A chimera of syntaxin 1A and syntaxin 2 in(More)
We evaluated the possible role of islet glucokinase in controlling the rate of islet glucose metabolism, and thereby the rate of glucose-induced insulin release. The activities of glucokinase, hexokinase, P-fructokinase, and glyceraldehyde-P dehydrogenase were quantitated in sonicated or isotonically homogenized islet preparations using pyridine(More)
Expression of the N-type voltage sensitive calcium channel in Xenopus oocytes along with syntaxin and p65 showed that the syntaxin-modified N-type channel properties, were fully reversed by p65. The inward current was restored to a significantly higher amplitude when all three proteins were present, suggesting that the channel interacts with syntaxin, p65(More)
We examined the relationship between glucose-induced insulin release and the intermediary metabolism of islets from fed and fasted rats. Isolated islets were perifused and insulin release measured in the effluent. At various times after switching islets from 2.4 to 8.6 or 14.5 mM glucose or from 2.4 to 14.5 and back to 2.4 mM glucose, islets were quickly(More)