Pisum sativum lectin or agglutinin (PSA) is isolated from peas. PSA has a molecular weight of around 53 kDa and is a heterodimer that consists of four subunits. It has an isoelectric point between pH 6.0 and pH 6.7. Pisum sativum agglutinin is nearly identical in structure and carbohydrate specificity to Lens culinarisagglutinin. It has a carbohydrate specificity towards alpha-mannose and alpha-glucose with an eluting sugar of alpha-methylglucoside + alpha-methylmannoside. Its hemagglutinating activity can be inhibited by glucose, mannose, and sucrose. It does not have a blood group specificity.

The N-terminal sequence of the lectin has shown some degree of homology compared to lectins from other legume species. Pisum sativum lectin has also shown mitogenic effect toward murine splenocytes and could inhibit activity of HIV-1 reverse transcriptase. PSA has been used to fractionate cells, to isolate glycoproteins and glycopeptides, to distinguish between normal and virally transformed cells, as a T-cell mitogen, and as an inhibitor of allograft rejection.