Ca2+ Signaling Proteins and Mammalian Sec6/8 Complex

Abstract

Polarized expression of signaling complexes requires mechanisms for delivery, assembly and retention of the proteins in the microdomains. Little or no information is available as to the nature of these mechanisms in non-excitable cells. It is possible that the vesicles/protein delivery system known as the exocyst or Sec6/8 complex participate in targeting the Ca2+ signaling complex to the microdomain. The data suggested by our work demonstrate that the Sec6/8 complex mediated delivery of pre-assembled Ca2+ signaling complexes to the apical pole region most proximal to the tight junctions. A novel function of the Sec6/8 complex is that the Sec6/8 complex has multiple roles in secretory cells including governing the polarized expression of Ca2+ signaling complexes and regulation of their activity.