Chick collapsin-1, the first identified vertebrate member of the semaphorin family of axon
guidance proteins, repels specific growth cones. Like all family members, collapsin-1
contains within its sequence a semaphorin domain that is necessary for specifying activity.
Two additional structural domains of collapsin-1, the immunoglobulin (Ig) domain and the
basic tail, each potentiate collapsin-1 activity. We identify in this study another structural
feature of collapsin-1 that is necessary for its function. Collapsin-1 covalently dimerizes, and …