Abstract
Glutamate release from rod photoreceptors is dependent on a sustained calcium influx through L-type calcium channels. Missense mutations in the CACNA1F gene in patients with incomplete X-linked congenital stationary night blindness implicate the Ca(v)1.4 calcium channel subtype. Here, we describe the functional and pharmacological properties of transiently expressed human Ca(v)1.4 calcium channels. Ca(v)1.4 is shown to encode a dihydropyridine-sensitive calcium channel with unusually slow inactivation kinetics that are not affected by either calcium ions or by coexpression of ancillary calcium channel beta subunits. Additionally, the channel supports a large window current and activates near -40 mV in 2 mM external calcium, making Ca(v)1.4 ideally suited for tonic calcium influx at typical photoreceptor resting potentials. Introduction of base pair changes associated with four incomplete X-linked congenital night blindness mutations showed that only the G369D alteration affected channel activation properties. Immunohistochemical analyses show that, in contrast with previous reports, Ca(v)1.4 is widely distributed outside the retina, including in the immune system, thus suggesting a broader role in human physiology.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
