Figure 4 Western Blot Analysis of ITPR1 Protein Levels in EBV Immortalized Lymphoblasts from AUS1 Family Members Western blot performed to examine ITPR1 levels in EBV immortalized lymphocytes from AUS1 affected family members carrying the ITPR1 deletion and from an AUS1 family member of unknown disease status who does not carry the deletion. Notably the samples from patients with ITPR1 deletion show a dramatic decrease in ITPR1 levels. To demonstrate equal loading, these samples were diluted one in five, and the Western blot was repeated using an antibody against ACTB. Itpr1 contains three domains, an N-terminal inositol triphosphate binding domain, a coupling domain, and a C-terminal transmembrane domain; it also contains two protein kinase A phosphorylation sites and an ATP-binding site.