Series was recorded, as well as the maximum speed achieved by the particle was also recorded. 1 particles were recorded per time series, as well as the typical speed and maximum speed had been calculated from the individual particles for each cell. This was repeated for any number of cells for every single situation, with each cell representing n 1 for error calculation. ElectrophysiologyXenopus oocytes had been ready, injected, and utilized for electrophysiology as described previously (29), together with the following exceptions. Plasmid cDNAs for the various CaV subunits, 1, 2 1, and 1b, were mixed in two:1:2 ratios at 1 g/ l, unless otherwise stated, and 9 nl was injected intranuclearly just after 2fold dilution on the cDNA mixes. Recordings in Xenopus oocytes had been performed as described (30), and all recordings were performed 48 60 h just after injection for CaV2.2. The Ba2 concentration was 10 mM. Currentvoltage plots have been fit having a modified Boltzmann equation, as described previously (30), for determination of the voltage for 50 activation (V50, act). Steadystate inactivation curves were match using a Boltzmann equation to decide the voltage for 50 inactivation (V50, inact) (30).RESULTSExpression and Properties of YFPCaV2.two and YFPCaV2.two(W391A)To be able to examine the trafficking of CaV2.two in neurons, we made tagged constructs, attaching GFP, YFP, or CFP for the N terminus, for both the WT and also the W391A mutant CaV2.2. We first examined the stability of those constructs by immunoblot following expression in tsA201 cells. No totally free YFP or CFP was observed ( supplemental Fig. 1, A and B), indicating that the fusion proteins were intact, as described previously for GFPCaV2.two (27). We then compared the properties of YFPCaV2.2 and YFPCaV2.two(W391A), collectively with all the accessory subunits two 1 and 1b, expressed in Xenopus oocytes. As expected, the W391A mutation reduced IBa quite substantially (supplemental Fig. 1C), by 81 at five mV and by 73 at 0 mV (supplemental Fig. 1D). This mutation also depolarized each the activation and steadystate inactivation curves, as expected for the absence of interaction of your III linker with subunits (supplemental Fig. 1, C and E). Comparable final results had been obtained previously in tsA201 cells for the nontagged channels (10), exactly where an 81 reduction in peak current density was observed for untagged CaV2.two(W3891A) compared using the WT channel. Importantly for our subsequent studies, CL 316243 Data Sheet coexpression of YFPCaV2.2 with YFPCaV2.2(W391A) did not cause any important suppression of CaV2.2 currents (supplemental Fig. 1D), as opposed to the dominant negative suppression that we observedVOLUME 286 Quantity 11 MARCH 18,9600 JOURNAL OF BIOLOGICAL CHEMISTRYSubunit Regulation of Calcium Channel DegradationFIGURE 1. Effect of coexpression of palmitoylated CaV2.2 III loop constructs on the subcellular distribution of GFPtagged CaV 1b in tsA201 cells. A, expression of 1bGFP alone. B, coexpression of 1bGFP and CaV2.2 III loop, palmitoylated on its N terminus (palm CaV2.two III WT). C, coexpression of 1bGFP and palmitoylated CaV2.2 III loop containing the W391A mutation (palm CaV2.two III W391A). In all pictures (A ), GFP is shown in green, and nuclear staining (DAPI) is shown in blue. Scale bars, 20 m. D, representative line scan fluorescence profiles of GFP (green) and DAPI (blue) for cells shown inside a ; for 1bGFP alone (left), 1bGFP plus palmitoylated CaV2.2 III loop (middle), and 1bGFP plus palmitoylated CaV2.two III loop containing the W391A mutation (proper). Fluorescence was measured along a typ.