Mouse natural killer cells express gp49B1, a structural homologue of human killer inhibitory receptors.
NK cells express MHC class I-specific receptors that inhibit tumor killing. In mice, these receptors belong to the highly polymorphic Ly-49 family, which are type II integral membrane proteins homologous to C-type lectins. In contrast, human killer inhibitory receptors (KIR) are type I transmembrane proteins that display minimal allelism and belong to the Ig superfamily. These structural differences suggested that each species evolved distinct receptors to subserve the same function. In this report, however, we show that mouse NK and LAK cells and NK cell clones express full-length transcripts for gp49B1, an immunoreceptor tyrosine-based inhibitory motif (ITIM)-containing type I transmembrane protein belonging to the Ig superfamily, and displaying minimal allelism by Southern and sequence analysis. By flow cytometry, gp49B1 is expressed on all NK cells. Therefore, we have established that gp49B1, a structural homologue of human KIR, is expressed on mouse NK cells. This strongly suggests that NK cells express two structurally distinct types of inhibitory receptors and that these receptors may act as coreceptors in mediating inhibition.
Wang
L L
LL
Department of Medicine and Pathology, Washington University School of Medicine, St. Louis, MO 63110, USA.
Mehta
I K
IK
LeBlanc
P A
PA
Yokoyama
W M
WM
D000818:Animals; D000950:Antigens, Ly; D001483:Base Sequence / Q000235:genetics; D015723:Gene Library; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis / Q000276:immunology; D015979:Killer Cells, Lymphokine-Activated / Q000378:metabolism; D007694:Killer Cells, Natural / Q000378:metabolism*; D037181:Lectins, C-Type; D008562:Membrane Glycoproteins / Q000096:biosynthesis*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D011971:Receptors, Immunologic / Q000096:biosynthesis* / Q000276:immunology; D054340:Receptors, KIR; D055630:Receptors, NK Cell Lectin-Like
D000950:Antigens, Ly; C489447:Gp49a protein, mouse; D007136:Immunoglobulins; D037181:Lectins, C-Type; C489448:Lilrb4 protein, mouse; D008562:Membrane Glycoproteins; D011971:Receptors, Immunologic; D054340:Receptors, KIR; D055630:Receptors, NK Cell Lectin-Like