Known calcium channel alpha1 subunits can form low threshold small conductance channels with similarities to native T-type channels.
نویسندگان
چکیده
Native T-type voltage-dependent calcium channels are low voltage-activated and have a small single channel conductance of 5-8 pS, which distinguishes them from any known cloned calcium channels whose conductances are 12-25 pS. Here, we show that when alpha1B, alpha1E, or alpha1C are expressed in COS7 cells, which contain no endogenous calcium channel subunits or calcium channels, they each exhibit a 4-7 pS channel as well as a large conductance channel. At low depolarizations, or when the alpha1 subunit is expressed in the absence of auxiliary alpha2-delta or beta subunits, the small conductance channels are seen alone, and their biophysical properties, including voltage dependence and kinetics of activation and inactivation, are very similar to native T-type calcium channels.
منابع مشابه
Known Calcium Channel α1 Subunits Can Form Low Threshold Small Conductance Channels with Similarities to Native T-Type Channels
The ␣ 1E clone has been put forward as a possible candidate for T-type current because it possesses some of the salient features, including low activation voltage, rapid inactivation, and similar or greater whole-cell current amplitude in Ca 2ϩ compared to Ba 2ϩ (Soong et al., 1993). Nevertheless, major discrepancies exist, the main Summary one being that the single channel conductance reported...
متن کاملMolecular physiology of low-voltage-activated t-type calcium channels.
T-type Ca2+ channels were originally called low-voltage-activated (LVA) channels because they can be activated by small depolarizations of the plasma membrane. In many neurons Ca2+ influx through LVA channels triggers low-threshold spikes, which in turn triggers a burst of action potentials mediated by Na+ channels. Burst firing is thought to play an important role in the synchronized activity ...
متن کاملTwo for T
Two for T Minireview other is more unexpected: a report that the already-known ␣ 1B , ␣ 1C , and ␣ 1E clones can produce single channel activity with many similarities to T-type channels Harvard Medical School Boston, Massachusetts 02115 (Meir and Dolphin, 1998). Perez-Reyes and colleagues identified the new clone by screening GenBank expressed sequence tags (ESTs) for homology to existing ␣ 1 ...
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متن کاملArt - Snutch (R)
407 The electrophysiological and pharmacological diversity of native calcium (Ca2+) channels (L, N, P, Q and T types) is well documented1. These subtypes have different functions; low-voltageactivated T-type channels shape action potentials and generate firing patterns2, whereas L-type channels regulate Ca2+-dependent genes and enzymes3,4, and N-type and P/Q-type channels contribute to neurotra...
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ورودعنوان ژورنال:
- Neuron
دوره 20 2 شماره
صفحات -
تاریخ انتشار 1998