Predicted maximum lengths of LIGHT, CD160, and BTLA stalk regions. The globular domains of LIGHT, CD160, and BTLA are shown as surface structures and colored as cyan, green, and blue, respectively. The CRDs of HVEM are shown as orange surfaces, and the remainder of the CRD regions that were not visible in the structures are shown as orange ovals. The cytoplasmic TNF receptor associated-factor (TRAF) molecule is shown as a gray surface. The stalk regions that connect the extracellular globular domains to the transmembrane segments are shown as lines. The maximum lengths of the stalk regions are calculated as if they adopt the fully extended structures. The length of the GPI-anchored CD160 stalk region in the figure does not include the GPI length. This figure indicates that when human membrane LIGHT binds to HVEM, the longer stalk lengths of LIGHT may prevent BTLA and CD160 binding to HVEM.