|Detection of Semaphorin 6A in Human T Cell Blasts by Flow Cytometry. Human T cell blasts were stained with Mouse Anti-Human Semaphorin 6A APC‑conjugated Monoclonal Antibody (Catalog # FAB1146A, filled histogram) or isotype control antibody (Catalog # IC0041A, open histogram). View our protocol for Staining Membrane-associated Proteins.|
The Semaphorins constitute a large family of secreted, glycosylphosphatidylinositol (GPI)-anchored and transmembrane cell signaling molecules. Depending on their domain organization and species origin, these proteins can be classified into eight groups. To date, at least 19 vertebrate Semaphorins belonging to five groups (class 3 to 7), have been identified. All Semaphorins contain a conserved 500 amino acid (aa) Sema domain at the amino-terminus. Semaphorins are best known for their roles in axon guidance during neuronal development. They are also expressed in non-neuronal tissues and are involved in angiogenesis, hematopoiesis, organogenesis, and the regulation of immune functions (1, 2). Class 6 Semaphorins (Sema 6) are transmembrane proteins that share homology with the axon-guiding insect Sema 1A. Human Sema 6A (VIa) cDNA predicts a 1,030 aa protein comprised of an extracellular domain, a transmembrane domain, and a long cytoplasmic tail (3, 4). A secreted form of Sema 6A can repel sympathetic and dorsal root ganglion axons in vitro, indicating a traditional role as an axon guidance signal (5). There is evidence, however, that Sema 6A also functions as a guidance receptor. Sema 6A mutants show a defect in thalamocortical neuron projection that is cell autonomous, and the cytoplasmic tails for Sema 6 contain binding sites for intracellular regulatory molecules such as Evl and Src (6).