Na+ channel protein, 4-beta subunit (SCN4B)

Function

• modulates channel gating kinetics of the voltage-gated Na+ channel
• causes negative shifts in the voltage dependence of activation of certain alpha Na+ channels, but does not affect the voltage dependence of inactivation (putative)
• contains a number of interchain disulfide bonds with SCN2A
• the voltage-sensitive Na+ channel consists of an ion conducting pore forming alpha-subunit regulated by one or more beta-1, beta-2, beta-3 &/or beta-4 subunits
• beta-1 & beta-3 are non-covalently associated with alpha, while beta-2 & beta-4 are covalently linked by disulfide bonds.
• associates with SCN2A

Structure

• contains 1 Ig-like C2-type domain (immunoglobulin-like)

Compartment

• membrane; single-pass type 1 membrane protein (probable)

Alternative splicing

named isoforms=2

Expression

• expressed at a high level in dorsal root ganglia, at a lower level in brain, spinal cord, skeletal muscle & heart

Pathology

• defects in SCN4B are the cause of long QT syndrome type 10 (LQT10)

More general terms

• voltage-dependent Na+ channel protein beta subunit

Component of

• voltage-dependent Na+ channel

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=6330
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:6330
• OMIM: https://mirror.omim.org/entry/608256
• OMIM: https://mirror.omim.org/entry/611819
• UniProt: http://www.uniprot.org/uniprot/Q8IWT1.html