Identification of a SEC22B binding domain within NBEAL2. (A) HA-tagged full-length (FL) NBEAL2 and fragments N1 to N5 (initial and terminal amino acids indicated, plus known functional domains) were individually coexpressed with FLAG-SEC22B in HEK293 cells. (B) HA-tagged proteins were immunoprecipitated from lysates and analyzed via immunoblots. Probing with anti-FLAG and anti-HA showed that FLAG-SEC22B pulled down FL HA-NBEAL2, N2 (aa 1798-2754), N3 (aa 1380-1903), and N5 (aa 1798-1903), but not N1 (aa 1-1145) or N4 (aa 1380-1797). These results indicate that a region within aa 1798 to 1903 of NBEAL2 can bind SEC22B. ARM, armadillo-like; ConA, concanavalin A-like; IgG, immunoglobulin G.