According to PubMed:15187158 isoform 4 is a receptor for the CD200 cell surface glycoprotein. According to PubMed:16081818 isoform 4 is not a receptor for the CD200/OX2 cell surface glycoprotein. Isoform 1, isoform 2 and isoform 3 are involved in the recruitment or surface expression of the TYROBP receptor. Isoform 6, isoform 7 and isoform 8 are not involved in the recruitment or surface expression of the TYROBP receptor.