Laboratory of Postharvest Science, Division of Bioproduction System Science, Department of Bioproduction Environmental Science, Faculty of Agriculture, Kyushu University
Laboratory of Postharvest Science, Division of Bioproduction System Science, Department of Bioproduction Environmental Science, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University
Laboratory of Postharvest Science, Division of Bioproduction System Science, Department of Bioproduction Environmental Science, Faculty of Agriculture, Kyushu University
九州大学農学部生産流通科学
Laboratory of Agricultural Process Engineering, Department of Agricultural Engineering, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University
九州大学大学院生物資源環境科学府
Laboratory of Postharvest Science, Division of Bioproduction System Science, Department of Bioproduction Environmental Science, Graduate School of Bioresource and Bioenvironmental Sciences, Kyushu University
九州大学大学院生物資源環境科学府生産流通科学
Laboratory of Postharvest Science, Division of Bioproduction System Science, Department of Bioproduction Environmental Science, Faculty of Agriculture, Kyushu University
九州大学農学部生産流通科学
A hybrld protein was synthesized by connecting bovine ribonuclease A (RNase A), an enzyme, and B chain of ricin, a toxic lectin from castor bean seeds, with a disulfide bridge. The preparation purified was revealed to contain one mole of RNase A and one mole of ricin B chain. The ricin B-RNase A hybrid was tested for cell binding, cellular uptake, and intoxication in four kinds of cells, rat liver and testis Leydig cells (normal and primarily cultured cells), and HeLa and BeWo cells (transformed cells). The ricin B-RNase A hybrid inhibited cellular protein synthesis equally in all four cells, while incubation of each cell mentioned above with RNase A or ricin B chain alone neither gave effect on cellular protein synthesis nor cell viability. This result inffered that the ricin B-RNase A hybrid first bound to the cell surface, internalized followed by the release of RNase A from the hybrid, resulting in the destruction of RNAs which play important roles in cellular protein synthesis. The degree of internalization of the ricin B-RNase A hybrid into cells was almost equal in four types of cells, about 10% of the bound hybrid. However, this value was about 1/3~1/2 that of ricin, a toxic lectin composed of A and B chains. From these results, ricin B-containing hybrid may be used as a universal tool to deliver a biologically active protein to a large number of different cells.