Ly6A/E is a member of the Ly-6 antigen family. The Thy-1lo, Lin- (lineage-negative, not expressing B220, Gr-1, Mac-1, CD4 or CD8), Sca-1+ population of bone marrow cells are highly purified, perhaps homogenous, pluripotent stem cells. This antigen is also present on various other tissues. Specific staining of the parenchymal cells can be demonstrated in thymus, spleen and kidney where as only vasculature reacts with anti-Sca-1 in brain, heart and liver (and possibly in lung). Also, Sca-1 is a T cell activation antigen, as surface expression of the antigen increases upon Con A activation of T lymphocytes. Sca-1 appears to have a molecular mass of 8 kDa under non-reducing conditions and 18 kDa under reducing conditions, indicating the presence of intra-chain disulfide bonds.Synonyms: Ly-6A.2/Ly-6E.1, Lymphocyte antigen 6A-2/6E-1, SCA-1, Stem cell antigen 1, T-cell-activating protein, TAP