SEMA5A belongs to the semaphorin gene family that encodes membrane proteins containing a semaphorin domain and several thrombospondin type-1 repeats. Members of this family are involved in axonal guidance during neural development. This gene has been implicated as an autism susceptibility gene.
The deduced 1,077-amino acid protein contains an N-terminal signal sequence, followed by a semaphorin domain, 7 thrombospondin type-1 repeats, a putative transmembrane domain, and a short cytoplasmic tail. It also has 13 conserved cysteines and a conserved N-glycosylation site. Northern blot analysis of whole mouse embryos detected 2 Semf transcripts at embryonic day 10, and their expression decreased toward birth.