Functions as a cell surface repellent for mossy fibers of developping neurons in the hippocampus where it plays a role in axon guidance (PubMed:20484647). May function through the PLXNA4 receptor expressed by mossy cell axons (PubMed:20484647). Homodimer (PubMed:9361278). Binds specifically the SH3 domain of the protooncogene C-SRC (PubMed:9361278). In adulthood, it is expressed ubiquitously. During development it is expressed in subregions of the nervous system and is particularly prominent in muscle (PubMed:9361278, PubMed:32169168). Expressed at embryonic day 18.5 dpc (PubMed:32169168). Mice lacking Sema6b are viable and fertile but display abnormal projection of hippocampal mossy fibers. Belongs to the semaphorin family.