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Updated: May 12, 2026

Comparing the Affinity of GTPase-binding Proteins using Competition Assays
Published on: October 8, 2015
Interaction characteristics of Plexin-B1 with Rho family proteins
Eyad Kalawy Fansa1, Radovan Dvorsky, Si-Cai Zhang
1Institut für Biochemie und Molekularbiologie II, Medizinische Fakultät der Heinrich-Heine-Universität, 40225 Düsseldorf, Germany.
Abstract:
Plexin-B1 regulates various cellular processes interacting directly with several Rho proteins. Molecular details of these interactions are, however, not well understood. In this study, we examined in vitro and in silico the interaction of the Rho binding domain (B1RBD) of human Plexin-B1 with 11 different Rho proteins. We show that B1RBD binds in a GTP-dependent manner to Rac1, Rac2, Rac3, Rnd1, Rnd2, Rnd3, and RhoD, but not to RhoA, Cdc42, RhoG, or Rif. Interestingly, Rnd1 competitively displaces the Rac1 from B1RBD but not vice versa. Structure-function analysis revealed a negatively charged loop region, called B1L(31), which may facilitate a selective B1RBD interaction with Rho proteins.
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