Structural domains comprising this superfamily share the structure of the F-spondin (FS) domain of spondins. Spondins are multi-domain extracellular matrix (ECM) protein as well as contact-repellent molecules that directs axon outgrowth and cell migration during development. Sponding patterns axonal growth trajectory by either inhibiting or promoting adhesion of embryonic nerve cells PMID:11287656. The FS domain is found in F-spondins, mindins, M-spondin and amphiF-spondin and its homology to a common Ca2+- and lipid-binding C2 domain suggests that the F-spondin FS domain is responsible for part of the membrane targeting of F-spondin in its regulation of axon development PMID:21569239.