Cluster of Differentiation 244 (CD244)

2B4, called also NKR2B4 [natural killer cell receptor 2B4] has been identified originally on mouse NK-cells and subsets of T-cells mediating nonMHC restricted cell killing. Murine NK-cells express two alternatively spliced isoforms, designated 2B4-S and 2B4-L. 2B4-S functions as an activating receptor, whereas 2B4-L is inhibitory. The new designation of this protein is CD244.

The 2B4 protein is expressed on all NK-cells, a subset of CD8(+) T-cells, basophils, mast cells, and monocytes. 2B4 is considered to be an activating receptor because cross-linking of 2B4 on NK-cells with a monoclonal antibody leads to NK-cell activation in vitro. However, 2B4 can also act as an inhibitory signaling receptor for NK-cells.