Involved in peripheral and central nervous system axon guidance. Acts as a receptor for Sema-2a and seems to transduce signal by suppressing Rac activity and enhancing Rho activity. Interacts with PlexA. Interacts with Rho1 and with the active forms of Rac1 and Rac2. Interacts with Sema-2a. Highly expressed in the embryonic and larval nervous system. Belongs to the plexin family.