Résumé
Genomic mining, the process of sifting through billions of genomic and EST sequences of several different species has led to the molecular identification of a family of low voltage activating channels, more commonly referred to as T-type channels. Historically, these channels were initially identified through the use of the patch-damp technique on various neuronal preparations. They were characterized by their small conductance, rapid voltage-dependent inactivation, a small window current and slow deactivation kinetics and their remarkable property of being able to open at membrane potentials just above the resting membrane potential of neurons. This property would allow for the entry of Ca2+ without the initiation of an action potential triggered by the opening of sodium channels. Thus the activity of these channels would contribute to modifying membrane excitability, allowing Ca2+ signaling events to occur at subthreshold potentials, and potentially modulate waveform patterns.
Now, with the clones in hand, we have entered an exciting time where the molecular machinery can be dissected, modified and manipulated not only to investigate their biophysical properties, but to appreciate their role in a diverse range of cellular processes, find novel and useful therapeutic and pharmacological reagents, hunt down subunits and modifying proteins, study their localization and trafficking and incorporate these findings into the emerging field of systems biology where their roles can be placed in the context from a single neuron, to the organ, to the organism.