Calcium channels: when is a subunit not a subunit?

Subunit of Voltage-activated Calcium Channels*

Voltage-activated Ca channels play a major role in many fundamental physiological processes including neurotransmission, muscle contraction, intracellular signaling, hormone secretion, and development. Therefore, an understanding of the structure and regulation of Ca channels is critical for the comprehension of these physiological phenomena. Five types of high voltage-activated Ca channels (na...

Gamma subunit of voltage-activated calcium channels.

Subunit structure of dihydropyridine-sensitive calcium channels from skeletal muscle.

Purified dihydropyridine-sensitive calcium channels from rabbit transverse-tubule membranes consist of three noncovalently associated classes of subunits: alpha (167 kDa), beta (54 kDa), and gamma (30 kDa). Cleavage of disulfide bonds reveals two distinct alpha polypeptides and an additional component, delta. The alpha 1 subunit, a 175-kDa polypeptide that is not N-glycosylated, contains the di...

Mechanism of Auxiliary Subunit Modulation of Neuronal α1E Calcium Channels

Voltage-gated calcium channels are composed of a main pore-forming alpha1 moiety, and one or more auxiliary subunits (beta, alpha2 delta) that modulate channel properties. Because modulatory properties may vary greatly with different channels, expression systems, and protocols, it is advantageous to study subunit regulation with a uniform experimental strategy. Here, in HEK 293 cells, we examin...

The α2δ Subunit and Absence Epilepsy: Beyond Calcium Channels?

BACKGROUND Spike-wave discharges, underlying absence seizures, are generated within a cortico-thalamo-cortical network that involves the somatosensory cortex, the reticular thalamic nucleus, and the ventrobasal thalamic nuclei. Activation of T-type voltage-sensitive calcium channels (VSCCs) contributes to the pathological oscillatory activity of this network, and some of the first-line drugs us...