SimaPrrin是一个保守的分泌和膜相关蛋白家族，在N-末端细胞外部分具有信号素（SEMA）结构域和PSI结构域（在丛蛋白、信号素和整合素中发现）。根据序列和结构的相似性，信号量可分为8类：无脊椎动物包含1类和2类，病毒包含5类，脊椎动物包含3-7类。SimaPrin通过多聚体受体复合物作为轴突导向配体，一些（如果不是全部）含有丛蛋白。这个基因编码一个4类信号量。这个基因编码一个3类信号量已发现该基因编码不同亚型的多个转录变体。[由RefSeq提供，2010年5月]
Semaphorins are a large family of conserved secreted and membrane associated proteins which possess a semaphorin (Sema) domain and a PSI domain (found in plexins, semaphorins and integrins) in the N-terminal extracellular portion. Based on sequence and structural similarities, semaphorins are put into eight classes: invertebrates contain classes 1 and 2, viruses have class V, and vertebrates contain classes 3-7. Semaphorins serve as axon guidance ligands via multimeric receptor complexes, some (if not all) containing plexin proteins. This gene encodes a class 4 semaphorin. This gene encodes a class 3 semaphorin. Multiple transcript variants encoding different isoforms have been found for this gene.[provided by RefSeq, May 2010]