A FAMILY OF MOLECULES RELATED TO COLLAPSIN IN THE EMBRYONIC CHICK NERVOUS-SYSTEM

Signaling molecules with either attractive or repulsive effects on spe cific growth cones are likely to play a role in guiding axons to their appropriate targets. A chick brain glycoprotein, collapsin, has been shown to be a good candidate for a repulsive guidance cue. We report h ere the discovery of four new molecules related to collapsin in chick brains. All contain a semaphorin domain. One is structurally very simi lar to collapsin but is only 50% identical in its amino acid sequence. We have named it collapsin-2. The collapsin-related genes exhibit dis tinct but overlapping patterns of mRNA expression in the developing sp inal cord and the developing visual system. This family of collapsin-r elated molecules could potentially act as repulsive cues toward specif ic neuronal populations.