Investigation of selenoprotein k function and associated proteins

Abstract

Selenoprotein K (SelK) is a small (16kD) single pass transmembrane protein localized to the ER. An Src Homology 3 (SH3)-binding domain within the amino acid sequence was exploited to identify potential protein-protein interactions. The effects of SelK deficiency in immune cells and effector calcium flux served as a model system to elucidate a function for SelK. Immunoprecipitation and mass spectrophotometry identification of potential binding partners returned Arf-GAP2 and pyruvate kinase as possible binding partners. Plasmid DNA vectors were designed for use in the Two-Hybrid system to confirm preliminary data of suspected interactions with the creation of fusion proteins coding for Vav1 or Vav2 SH3 domain and the SelK SH3 binding domain. Protein-protein interaction could not be confirmed in this system however SelK seems to play a role in receptor mediated calcium flux, and subsequent low-level production of nitric oxide by way of neuronal nitric oxide synthase.