Composition and immunochemical properties of glycoproteins with anti-B agglutinin activity isolated from Euonymus sieboldiana seeds

The "old" Euonymus europaeus agglutinin represents a novel family of ubiquitous plant proteins

Molecular cloning of the "old" but still unclassified Euonymus europaeus agglutinin (EEA) demonstrated that the lectin is a homodimeric protein composed of 152 residue subunits. Analysis of the deduced sequence indicated that EEA is synthesized without a signal peptide and undergoes no posttranslational processing apart from the removal of a six-residue N-terminal peptide. Glycan array screening confirmed the previously reported high reactivity of EEA toward blood group B oligosaccharides but also revealed binding to high mannose N-glycans, providing firm evidence for the occurrence of a plant carbohydrate-binding domain that can interact with structurally different glycans. Basic Local Alignment Search Tool searches indicated that EEA shares no detectable sequence similarity with any other lectin but is closely related evolutionarily to a domain that was first identified in some abscisic acid- and salt stress-responsive rice (Oryza sativa) proteins, and, according to the available sequence data, might be ubiquitous in Spermatophyta. Hence, EEA can be considered the prototype of a novel family of presumably cytoplasmic/nuclear proteins that are apparently ubiquitous in plants. Taking into account that some of these proteins are definitely stress related, the present identification of the EEA lectin domain might be a first step in the recognition of the involvement and importance of protein-glycoconjugate interactions in some essential cellular processes in Embryophyta.

Inhibitory activities of substances present in plant seeds and fruits against anti-Lewis agglutinins

Thirty-six species of higher plants were found to contain substances in their fruit or seed extracts, which were heat stable and inhibitory for anti-Lea agglutinin. Both preparations partially fractionated from Sophora japonica and Euonymus Sieboldiana were also slightly inhibitory for anti-Leb agglutinin.