Biochemical assessment of α-α-subunit interactions of Nav1.5 in a heterologous expression system

Abstract

Heterologous overexpression of any protein, and especially of the large transmembrane channel Nav1.5, could be associated with the insufficiency of endoplasmic reticulum folding machinery, hence leading to aspecific protein aggregation indistinguishable from the genuine --subunit interactions. In this study, we show that the interactions between heterologous Nav1.5 proteins depend on nascent N-linked glycosylation, are supported by non-native intermolecular disulfide bonds, and are likely predisposed to hydrophobic "stickiness". Particularly, we show strong interactions between the full-length Nav1.5 and its truncated peptides: N-terminal domain, all four transmembrane domains, as well as the intracellular linker between domains I and II. Taken together, we conclude that the heterologous expression system is not optimal for the identification of --subunit interaction sites of Nav1.5, and this question needs to be further addressed in the native tissues. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=130 SRC="FIGDIR/small/679760v1_ufig1.gif" ALT="Figure 1"> View larger version (21K): org.highwire.dtl.DTLVardef@b29b7dorg.highwire.dtl.DTLVardef@1fe5909org.highwire.dtl.DTLVardef@1877990org.highwire.dtl.DTLVardef@13e04b3_HPS_FORMAT_FIGEXP M_FIG C_FIG