Several lines of evidence suggest different allocations of the physiological roles of aminopropyl tranferase genes, SPMS and ACL5 in plants. To get deeper insights into the physiological role of apple ACL5 (MdACL5), we performed yeast two-hybrid (Y2H) assay to identify proteins which interact with MdACL5. After intense screening processes, including the swapping of the bait and prey vectors and in vitro coimmunoprecipitation, we identified three MdACL5-interacting proteins: putative translation elongation factor 1A (eEF-1A), putative S-adenosyl-L-methionine synthetase (SAMS) and an unknown protein. Results from Y2H and RNA gel blot analysis suggested the involvement of MdACL5 and eEF-1A or SAMS complexes in the plant growth and development of the organized tissues and/or organs. (c) 2007 Elsevier Inc. All rights reserved.