The toxin abrin is a dimer consisting of two protein subunits, termed A and B. The B chain facilitates abrin's entry into a cell by bonding to certain transport proteins on cell membranes, which then transport the toxin into the cell. Once inside the cell, the A chain prevents protein synthesis by inactivating the 26S subunit of the ribosome. One molecule of abrin will inactivate up to 1,500 ribosomes per second. Symptoms are identical to those of ricin, except abrin is more toxic by almost two orders of magnitude; the fatal dose of abrin is approximately 75 times smaller than the fatal dose of ricin...Photo via A London Salmagundi.
The seeds of Abrus precatorius are much valued in native jewelry for their bright coloration. Most beans are black and red, suggesting a ladybug, though other colors are available. Jewelry-making with jequirity seeds is dangerous, and there have been cases of death by a finger-prick while boring the seeds for beadwork.
06 December 2011
Native mask decorated with lethal seeds
Metropolitan Museum of Art. The black and red sprinkles are apparently abrus seeds - which is interesting in an of itself, because a quick search reveals that the seeds are more toxic than ricin: