LRP1 influences trafficking of N-type calcium channels via interaction with the auxiliary ?₂?-1 subunit.

ABSTRACT: Voltage-gated Ca²⁺ (Ca_V) channels consist of a pore-forming ?1 subunit, which determines the main functional and pharmacological attributes of the channel. The Ca_V1 and Ca_V2 channels are associated with auxiliary ?- and ?₂?-subunits. The molecular mechanisms involved in ?₂? subunit trafficking, and the effect of ?₂? subunits on trafficking calcium channel complexes remain poorly understood. Here we show that ?₂?-1 is a ligand for the Low Density Lipoprotein (LDL) Receptor-related Protein-1 (LRP1), a multifunctional receptor which mediates trafficking of cargoes. This interaction with LRP1 is direct, and is modulated by the LRP chaperone, Receptor-Associated Protein (RAP). LRP1 regulates ?₂? binding to gabapentin, and influences calcium channel trafficking and function. Whereas LRP1 alone reduces ?₂?-1 trafficking to the cell-surface, the LRP1/RAP combination enhances mature glycosylation, proteolytic processing and cell-surface expression of ?₂?-1, and also increase plasma-membrane expression and function of Ca_V2.2 when co-expressed with ?₂?-1. Furthermore RAP alone produced a small increase in cell-surface expression of Ca_V2.2, ?₂?-1 and the associated calcium currents. It is likely to be interacting with an endogenous member of the LDL receptor family to have these effects. Our findings now provide a key insight and new tools to investigate the trafficking of calcium channel ?₂? subunits.

SUBMITTER: Kadurin I 

PROVIDER: S-EPMC5335561 | biostudies-literature | 2017 Mar

REPOSITORIES: biostudies-literature