1. Adding Membranes to Synapses
David Gorczyca, James Ashley, Sean Speese, Norberto Gherbesi, Ulrich Thomas, Eckart Gundelfinger, L. Sian Gramates, and Vivian Budnik
Nothing is a more fundamental operation than addition, even when it comes to synaptic membranes. This week, Gorczyca et al. addressed the complex process of targeted membrane addition at the larval Drosophila neuromuscular junction, particularly the specialized, multilayered postsynaptic membrane called the subsynaptic reticulum (SSR). The authors used the guanylate kinaselike domain of the fly scaffolding protein Discs-Large (DLG) as bait in a yeast two-hybrid screen. They isolated guanylate kinase-interacting syntaxin [Gtaxin (GTX)]. GTX colocalized with DLG at postsynaptic glutamatergic type I boutons but not at type II and III boutons. GTX and DLG interacted in vivo, and targeting of GTX to the SSR depended on DLG. Like dlg mutants, gtx mutants exhibited a severely compromised SSR. Overexpression of GTX resulted in the formation of extrasynaptic SSR-like structures independent of DLG, indicating a role for GTX in membrane addition.
2. Drosophila Cacophony Channels
I-Feng Peng and Chun-Fang Wu
In the second of three papers using Drosophila in This Week in the Journal, Peng and Wu cataloged the diverse properties of calcium channel currents encoded by the cacophony (cac) locus. The authors made whole-cell voltage-clamp and current-clamp recordings from cultured giant neurons, generated from fly embryo cells in which cytokinesis had been halted. Recordings from neurons in wildtype and two cac mutants, cacs and cacts2, showed that cac currents varied in their kinetics, displaying low- and high-voltage activation and both fast and slow inactivation. Interestingly, the currents were sensitive to T-type but not L-type calcium channel blockers. Calcium entry through
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Society for Neuroscience