Close homolog of L1 (CHL1) is a member of the L1 family of cell adhesion molecules expressed by subpopulations of neurons and glia in the central and peripheral nervous system. CHL1 like L1 promotes neuron survival and neurite outgrowth. CHL1 shares the basic structural arrangement of L1 family members yet in contrast to all the members it is not capable of forming homophilic adhesion. The second Ig-like domain of CHL1 contains the integrin interaction motif RGD rather than with in the sixth Ig-like domain as in L1, however the sixth Ig-like domain of CHL1 has another potential integrin binding motif DGEA. CHL1 binds NP-1 via the Ig1 sequence FASNRL to mdediate repulsive axon guidance to Sema3A. CHL1 is the only L1 family member with an altered sequence (FIGAY) in the ankyrin-binding domain, and it lacks the sorting/endocytosis RSLE motif, which is characteristic of other L1 family members.