DR. D'ADAMO: LECSTER 7

The lectin database of Dr. Peter D'Adamo.
BACK TO INDEX | LECSTER7 FAQ

Abrus precatorius
SPECIES IMAGE
SOURCE	Jequirity bean;
LECTINS	APA; APA-A; APA-C; Abrin
MOLECULAR IMAGE
CLASS	beta-trefoil lectin (APA); Type 2 RIP
NOMEN	LECp.Abr.Pre.se.Cga1
INDEX	Plant lectin / Plant / Seed / Chimerolectin / Gal/GalNAc-binding lectins
CHARACTERIZATION	The Jequirity, also called Black-eyed Susan, Rosary Pea or Indian Licorice (Abrus precatorius), is a legume with long, pinnate-leafleted leaves. Their seeds are often used as beads and in percussion instruments. The seed is highly poisonous but is unlikely to harm if swallowed raw and unbroken, as they have a hard seed coat. The toxin present in abrus precatorius is a close relative to ricin called abrin. It is a dimer consisting of two protein subunits, termed A and B. The B chain is abrin's ticket into the cell: it bonds to certain transport proteins on cell membranes, which then transport the toxin into the cell. Once inside the cell, the A 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 that the fatal dose of ricin is approximately 75 times greater than the fatal dose of abrin. Abrin can kill with a circulating amount of less than 3 μg (micrograms). The seeds of abrus precatorius are much valued in native jewelry for their bright coloration. The third of the bean with the hilum (attachment scar) is black, while the rest is bright red, suggesting a ladybug. Jewelry-making with jequirity seeds is dangerous, and there have been cases of death by a finger-prick while boring the seeds for beadwork.
BIOACTIVITY	Seeds of Abrus precatorius contain two distinct but structurally related Type 2 RIPs. Abrin is an extremely potent toxin but a weak agglutinin, whereas APA is a potent erythroagglutinin with relatively low cytotoxicity. For characterizations of APA-I and APA-II see: Anal Biochem 1991 Apr;194(1):101-9) Abrin has anti-carcenogenic activity. See: Cancer Research 1982 (42)276-27 Compared with the Abrus lectin, which strongly agglutinates rabbit erythrocytes and human A,B and O erythrocytes, abrin shows only weak aggltuinating activity. See:Eur. J. Biochem 1973 (35)179-185 ABA is a potent mitogen to thymus derived lymphocytes. See: Meth. Enzymol. 1978 (50)323-330
SOURCE TISSUE	Seed
SPECIFICITY	Gal(Galb(1,3), GalNAcb1-(Thomsen-Friedenreich Structure)>Gal
INHIBITORS	d-galactose
REFERENCES	J. Biol. Chem 1974. (249) 3061

DR. D'ADAMO: LECSTER 7

Abrus precatorius