Several non‐myrosinase proteins have been found in association with some of the myrosinases extracted from rape (Brassica napus) seed. Most of these proteins seemed to belong to a large family of proteins ranging in size over approximately 30–110 kDa, namely the myrosinase‐binding protein (MBP) family. Potentially all of these MBPs might be derived from a single large precursor, encoded by a 3.3‐kb transcript. This transcript coded for a 99‐kDa glycine‐rich protein with a highly repetitive structure. The mature 50‐kDa and 52‐kDa MBP amino‐terminal was located 255 amino acids from the putative initiation methionine. Also, a more divergently related transcript, the protein product of which was unknown, has been cloned. However, the largest open reading frame suggested a proline‐rich protein. While this transcript seemed to be expressed predominantly in seeds, the MBP transcripts were expressed in several tissues and also exhibited a responsiveness to wounding and methyl jasmonate. Both proteins exhibited significant similarities to lectins from Artocarpus integer and from Maclura pornifera.