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Proceedings of the National Academy of Sciences of the United States of America logoLink to Proceedings of the National Academy of Sciences of the United States of America
. 1985 Jul;82(14):4847–4851. doi: 10.1073/pnas.82.14.4847

A large intracellular pool of inactive Na channel alpha subunits in developing rat brain.

J Schmidt, S Rossie, W A Catterall
PMCID: PMC391002  PMID: 2410908

Abstract

An intracellular pool of Na channel alpha subunits has been detected in developing brain cells in vivo and in vitro by phosphorylation with cAMP-dependent protein kinase, immunoprecipitation with specific antiserum, and NaDodSO4 gel electrophoresis or by radioimmunoassay. These alpha subunits are membrane-bound, contain complex carbohydrate chains, and have an apparent molecular weight of 260,000 like mature alpha subunits. In contrast to mature alpha subunits, the intracellular subunits are not covalently attached to a beta 2 subunit, and they do not bind saxitoxin with high affinity. They comprise 67-77% of the total immunoreactive alpha subunit in developing rat brain cells but are not a prominent component in the adult brain. It is proposed that this intracellular pool of alpha subunits forms a ready reserve of preformed subunits for incorporation into the surface membrane during periods of active membrane biogenesis. The results suggest that disulfide linkage of the alpha and beta 2 subunits, insertion into the cell surface membrane, and attainment of a functional conformation are closely related late events in the biogenesis of the Na channel. These processes may regulate the number of functional Na channels in the developing brain.

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Selected References

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