Phaseolus vulgaris agglutinin is the name ascribed to a family of lectins, each of which consists of four subunits. There are two different types of subunits. One appears to be involved primarily in red cell agglutination and has been designated the “E” subunit (for erythroagglutinin). The other type is involved in lymphocyte agglutination and mitogenic activity and has been termed the “L” subunit (for leucoagglutinin). These subunits combine to produce five isolectins. PHA-L, with four "L" type subunits, does not agglutinate red cell but is a potent mitogen.
Biotinylated PHA-L has an appropriate number of biotins bound to provide the optimum staining characteristics for this lectin. This conjugate is supplied essentially free of unconjugated biotins and is preserved with sodium azide.
I recently purchased a biotinylated lectin. The datasheet supplied with the lectin suggests including 0.1 mM Ca++as part of the recommended buffer to prepare a working solution. What should I specifically add, and why is this required?
From our experience we have found that some lectins require Ca++ to be present for optimal binding activity. We suggest using calcium chloride (CaCl2) to fortify working solutions and ensure a minimum level of Ca++ is meet. This may be particularly pertinent if using phosphate based buffers as diluents and storage solutions.
PHA-L, with four L type subunits, does not agglutinate red cells but is a potent mitogen. The other three isolectins, designated E3L1, E2L2, and E1L3, have erythroagglutinating and mitogenic activities proportional to the number of respective E or L subunits. We have termed the mixture of the five isolectins PHA (E+L).
This biotinylated lectin is an ideal intermediate for examining glycoconjugates using the Biotin-Avidin/Streptavidin System. First the biotinylated lectin is added, followed by the VECTASTAIN ABC Reagent, Avidin D conjugate, or streptavidin derivative.
Note: Do not use a biotinylated PHA-L to perform anterograde neuronal tracing. Only the unconjugated PHA-L (catalog # L-1110) is compatible for this application.