The novel product of a five-exon stargazin-related gene abolishes Ca(V)2.2 calcium channel expression.
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Moss FJ, Viard P, Davies A, Bertaso F, Page KM, Graham A, Canti C, Plumpton M, Plumpton C, Clare JJ, Dolphin AC
The novel product of a five-exon stargazin-related gene abolishes Ca(V)2.2 calcium channel expression.
EMBO J. 2002 Apr 2;21(7):1514-23.
- PubMed ID
- 11927536 [ View in PubMed]
- Abstract
We have cloned and characterized a new member of the voltage-dependent Ca(2+) channel gamma subunit family, with a novel gene structure and striking properties. Unlike the genes of other potential gamma subunits identified by their homology to the stargazin gene, CACNG7 is a five-, and not four-exon gene whose mRNA encodes a protein we have designated gamma(7). Expression of human gamma(7) has been localized specifically to brain. N-type current through Ca(V)2.2 channels was almost abolished when co-expressed transiently with gamma(7) in either Xenopus oocytes or COS-7 cells. Furthermore, immunocytochemistry and western blots show that gamma(7) has this effect by causing a large reduction in expression of Ca(V)2.2 rather than by interfering with trafficking or biophysical properties of the channel. No effect of transiently expressed gamma(7) was observed on pre-existing endogenous N-type calcium channels in sympathetic neurones. Low homology to the stargazin-like gamma subunits, different gene structure and the unique functional properties of gamma(7) imply that it represents a distinct subdivision of the family of proteins identified by their structural and sequence homology to stargazin.