Merck, 11249738001, Phytohemagglutinin-L (PHA-L)

PHA-L is purified from Phaseolus vulgaris (red kidney bean) by standard chromatographic techniques. Phytohemagglutinin (PHA), the lectin extract from the red kidney bean, consists of only L-type subunits (isolectin L4, \leuko-agglutinin\). It is an N-acetylgalactosamine/galactose sugar-specific lectin. PHA consists of five isolectins (L4E0, L3E1, L2E2, L1E3, L0E4) each being a tetramer held together by noncovalent forces. The subunits L (leukocyte reactive) have a high affinity for lymphocyte surface receptors, but little for those of erythrocytes, and are responsible for the mitogenic properties of the isolectins. E (erythrocyte reactive) is responsible for the erythrocyte-agglutinating properties.