The immunoglobulin domain of the sodium channel β3 subunit contains a surface-localized disulfide bond that is required for homophilic binding.

ABSTRACT: The β subunits of voltage-gated sodium (Na(v)) channels possess an extracellular immunoglobulin (Ig) domain that is related to the L1 family of cell-adhesion molecules (CAMs). Here we show that in HEK293 cells, secretion of the free Ig domain of the β3 subunit is reduced significantly when it is coexpressed with the full-length β3 and β1 subunits but not with the β2 subunit. Using immunoprecipitation, we show that the β3 subunit can mediate trans homophilic-binding via its Ig domain and that the β3-Ig domain can associate heterophilically with the β1 subunit. Evolutionary tracing analysis and structural modeling identified a cluster of surface-localized amino acids fully conserved between the Ig domains of all known β3 and β1 sequences. A notable feature of this conserved surface cluster i

SUBMITTER: Yereddi NR 

PROVIDER: S-EPMC3583845 | biostudies-literature | 2013 Feb

REPOSITORIES: biostudies-literature