A novel ADP-ribosylation like factor (ARL-6), interacts with the protein-conducting channel SEC61 beta subunit

We report here the isolation of a new member of the ADP-ribosylation factor (ARF)-like family (ARL-6) present in the J2E erythroleukemic cell line, bu t not its myeloid variants, Consistent with this lineage-restricted express ion, ARL-6 mRNA increased with erythropoietin-induced maturation of J2E cel ls, and decreased with interleukin 6-induced differentiation of M1 monoblas toid cells. In tissues, ARL-6 mRNA was most abundant in brain and kidney. W hile ARL-6 protein was predominantly cytosolic, its membrane association in creased following exposure to GTP-gamma S, like many members of the ARF/ARL family. Using the yeast two-hybrid system, six molecules which interact wi th ARL-6 were identified including SEC61 beta, a subunit of the heterotrime ric protein conducting channel SEC61 beta, Co-immunoprecipitation of ARL-6 confirmed a stable association between ARL-6 and SEC61 beta in COS cells. T hese results demonstrate that ARL-6, a novel member of the ADP-ribosylation factor-like family, interacts with the SEC61 beta subunit, (C) 1999 Federa tion of European Biochemical Societies.