Usui et al. (2003) found in yeast two-hybrid screening that an intracellular 349 amino acid fragment of plexin-B1 is interacting with plexin-A1. Furthermore, in a mammalian expression system Plexin-B1 physically associated with plexin-A1, but not with plexin-A2 or A3. They proposed that plexin-A1 and B1 interact in the adult brain and transduce Sema3A signaling in cooperation.
Gioradano et al (2002) found that binding of Sema 4D to Plexin B1 stimulates the tyrosine kinase activity of Met, resulting in tyrosine phosphorylation of both receptors. Furthermore, cells lacking Met expression do not respond to Sema 4D unless exogenous Met is expressed.