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The novel product of a five‐exon stargazin ‐related gene abolishes Ca V 2.2 calcium channel expression
Author(s) -
Moss Fraser J.,
Viard Patricia,
Davies Anthony,
Bertaso Federica,
Page Karen M.,
Graham Alex,
Cantí Carles,
Plumpton Mary,
Plumpton Christopher,
Clare Jeffrey J.,
Dolphin Annette C.
Publication year - 2002
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/21.7.1514
Subject(s) - library science , biology , sociology , computer science
We have cloned and characterized a new member of the voltage‐dependent Ca 2+ channel γ subunit family, with a novel gene structure and striking properties. Unlike the genes of other potential γ 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 γ 7 . Expression of human γ 7 has been localized specifically to brain. N‐type current through Ca V 2.2 channels was almost abolished when co‐expressed transiently with γ 7 in either Xenopus oocytes or COS‐7 cells. Furthermore, immunocytochemistry and western blots show that γ 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 γ 7 was observed on pre‐existing endogenous N‐type calcium channels in sympathetic neurones. Low homology to the stargazin‐like γ subunits, different gene structure and the unique functional properties of γ 7 imply that it represents a distinct subdivision of the family of proteins identified by their structural and sequence homology to stargazin.