Channeling Vision: Ca1.4-A Critical Link in Retinal Signal Transmission.

Voltage-gated calcium channels (VGCC) are key to many biological functions. Entry of Ca into cells is essential for initiating or modulating important processes such as secretion, cell motility, and gene transcription. In the retina and other neural tissues, one of the major roles of Ca-entry is to stimulate or regulate exocytosis of synaptic vesicles, without which synaptic transmission is impaired. This review will address the special properties of one L-type VGCC, Ca1.4, with particular emphasis on its role in transmission of visual signals from rod and cone photoreceptors (hereafter called "photoreceptors," to the exclusion of intrinsically photoreceptive retinal ganglion cells) to the second-order retinal neurons, and the pathological effects of mutations in the gene which codes for the pore-forming α subunit of Ca1.4.