Figure 1.

The vertebrate semaphorins and their main receptors. The main structural features of the subfamilies of the vertebrate semaphorins and their receptors are shown. The members of the vertebrate semaphorin family all contain the hallmark Sema domain and are divided into five subfamilies based upon structural features. The Class-3 semaphorins are the only secreted semaphorins. The main receptors for semaphorins are listed below. For most Class-3 semaphorins, neurophilins and plexins are their receptors. For Class-4 semaphorins, the main receptors are PlexinB molecules, while PlexinC1, PlexinD1, and neuropilins can also act as their receptors. For the only member of Sema7, PlexinC1 and integrin β1 are the main receptors. Many other molecules including integrin, proteoglycans, and RTKs have also been included as receptors for semaphorins, which are not showed in the diagram.