Biogenesis and subcellular transport of calcium channels
Voltage-activated calcium channels open in response to membrane depolarization allowing the entry of calcium ions into excitable cells that in turn triggers multiple cellular events including neurotransmission, excitation-contraction coupling, gene expression and hormone secretion. To mediate these heterogeneity of biological actions, these channels are targeted to specific sites at the plasma membrane where they form supramolecular assemblies containing diverse regulatory and protein effectors that couple the influx of calcium to a particular downstream signal cascade.The task of the intracellular transport machinery is to deliver functional channels at the right place and at the right time. The life of the channel protein starts in the endoplasmic reticulum. Here channels that have approved a quality control begin their intracellular journey to their final destination. For this channels are packed into vesicles that actively navigate through the dense network of actin- and tubulin-based cytoskeleton that serve as tracks for the intracellular trafficking. Mature channels assembled at the plasma membrane are finely regulated for their permeation properties until they are removed from the cell surface by endocytosis. A second quality control may decide their sorting fate after internalization: either the channel is recycled back to the plasma membrane or derived to the degradation pathway.Our research is aimed at understanding regulation of the voltage-activated calcium channel at all stages of its life cycle; during its biogenesis, intracellular trafficking toward and from the plasma membrane and at the plasma membrane. We combine molecular biology, protein biochemistry, electrophysiology and laser scanning and spinning disk microscopy to study and track fluorescently labeled calcium channels in living cells.