Human Semaphorin 4A Alexa Fluor™ Plus 680‑conjugated Antibody

Sema4A (Semaphorin 4A; also Sema B) is a class IV member of the semaphorin family of proteins. It is expressed by dendritic cells, monocytes, T cells, B cells, astrocytes and oligodendrocytes, plus visceral smooth muscle and bronchial epithelial cells. It reportedly binds to Tim-2 and Plexin D1 and B1. In the immune system, it serves to activate naïve T cells and induce a Th1 phenotype. In the nervous system, it induces growth cone collapse in neurons. Mature human Sema4A is an 80 kDa (predicted) type I transmembrane glycoprotein that is 729 amino acids (aa) in length (aa 33-761). It contains a 651 aa extracellular region (aa 33-683) that is characterized by the presence of one Sema domain (aa 36-494), a PSI region (aa 496-528), and an Ig-like C2-type domain (aa 573-631). The 57 aa cytoplasmic region contains two potential phosphorylation sites at Thr744 and Ser747. There are two potential splice variants. One contains a 37 aa substitution for aa 293-328, while a second contains an alternative start site at Met100 coupled to a deletion of aa 122-154. Sema4A is reportedly cleaved to generate both a monomeric and a  dimeric soluble isoforms. Over aa 32-683, human Sema4A shares 86% aa identity with mouse Sema4A.