Investigation of the interaction between calreticulin and immunoglobulin G by capillary electrophoresis and computer modeling

Calreticulin (CRT), a highly conserved ubiquitous multifunctional protein, has immense implications in physiological, developmental, and pathological processes due to its interaction with many proteins. In this work, we utilized various capillary electrophoresis (CE) modes for CRT analysis and its interaction with IgG both qualitatively and quantitatively. The interaction was evaluated by capillary zone electrophoresis (CZE) and affinity capillary electrophoresis (ACE) modes that took only 4–6 min for each run. The nanomolar level K_d was determined between CRT and IgG by CZE-LIF and ACE-UV, whereas, CRT did not exhibit any interaction with HSA (as the control protein). By computer modeling, we obtained modeled structures of the CRT-IgG complex which mapped six hot spots on the CRT and IgG interacting interface. Our work is the first report which establishes CE methods for qualitative and quantitative analysis of CRT and IgG interaction. Moreover, the results of computer modeling provide the first molecular insights into the CRT binding sites for IgG that may act as the key anchors and contribute to the interaction studies between CRT and its interacting protein partners.