V domain of human SLAM (CDw150) is essential for its function as a measlesvirus receptor

Human signaling lymphocytic activation molecule (SLAM; also known as CDw150 ) has been shown to be a cellular receptor for measles virus (MV). Chinese hamster ovary cells transfected with a mouse SLAM cDNA were not susceptible to MV and the vesicular stomatitis virus pseudotype bearing MV envelope pr oteins alone, indicating that mouse SLAR I cannot act as an MV receptor. To determine the functional domain of the receptor, we tested the abilities o f several chimeric SLAM proteins to function as MV receptors. The ectodomai n of SLAM comprises the two immunoglobulin superfamily domains (V and C2). Various chimeric transmembrane proteins possessing the V domain of human SL AM mere able to act as MV receptors, whereas a chimera consisting of human SLAM containing the mouse V domain instead of the human V domain no longer acted as a receptor. To examine the interaction between SLAM and MV envelop e proteins, recombinant soluble forms of SLAM were produced. The soluble mo lecules possessing the V domain of human SLAM were shown to bind to cells e xpressing the MV hemagglutinin (H) protein but not to cells expressing the MV fusion protein or irrelevant envelope proteins. These results indicate t hat the V domain of human SLAM is necessary and sufficient to interact with the MV H protein and allow MV entry.